https://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&feed=atom&action=historyZ80 - Revision history2024-03-29T14:09:05ZRevision history for this page on the wikiMediaWiki 1.39.6https://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=2243&oldid=prevGuesser at 18:24, 26 May 20212021-05-26T18:24:30Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Test programs ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Test programs ==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>A basic Flags test program for emulators is available [http://homepage.ntlworld.com/mark.woodmass/z80tests.tap here]. Note that the program makes heavy use of ROM data during the tests and so should only be used with an unpatched copy of the original 48K ROM to obtain correct results.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>A basic Flags test program for emulators is available [<ins style="font-weight: bold; text-decoration: none;">https://web.archive.org/web/20130511214919/</ins>http://homepage.ntlworld.com/mark.woodmass/z80tests.tap here]. Note that the program makes heavy use of ROM data during the tests and so should only be used with an unpatched copy of the original 48K ROM to obtain correct results.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Patrik Rak has written a [http://zxds.raxoft.cz/taps/misc/z80test.zip Z80 instruction tester], as [https://www.worldofspectrum.org/forums/showthread.php?t=41834 announced here].</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Patrik Rak has written a [http://zxds.raxoft.cz/taps/misc/z80test.zip Z80 instruction tester], as [https://www.worldofspectrum.org/forums/showthread.php?t=41834 announced here].</div></td></tr>
</table>Guesserhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=2054&oldid=prevZub: Let's (really) use HTTPS!2020-05-10T14:15:12Z<p>Let's (really) use HTTPS!</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:15, 10 May 2020</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([https://archive.computerhistory.org/resources/text/Oral_History/Zilog_Z80/102658073.05.01.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([https://archive.computerhistory.org/resources/text/Oral_History/Zilog_Z80/102658073.05.01.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[https://zeptobars.com/en/read/t34vm1-z80-angstrem-mme], and the КР1858ВМ1 in Cyrillic (KR1858VM1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[<del style="font-weight: bold; text-decoration: none;">http</del>://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[https://zeptobars.com/en/read/t34vm1-z80-angstrem-mme], and the КР1858ВМ1 in Cyrillic (KR1858VM1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[<ins style="font-weight: bold; text-decoration: none;">https</ins>://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=2001&oldid=prevZub: Let's (really) use HTTPS!2020-05-10T10:43:42Z<p>Let's (really) use HTTPS!</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 10:43, 10 May 2020</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([https://archive.computerhistory.org/resources/text/Oral_History/Zilog_Z80/102658073.05.01.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([https://archive.computerhistory.org/resources/text/Oral_History/Zilog_Z80/102658073.05.01.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[<del style="font-weight: bold; text-decoration: none;">http</del>://zeptobars.<del style="font-weight: bold; text-decoration: none;">ru</del>/en/read/t34vm1-z80-angstrem-mme], and the КР1858ВМ1 in Cyrillic (KR1858VM1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[http://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[<ins style="font-weight: bold; text-decoration: none;">https</ins>://zeptobars.<ins style="font-weight: bold; text-decoration: none;">com</ins>/en/read/t34vm1-z80-angstrem-mme], and the КР1858ВМ1 in Cyrillic (KR1858VM1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[http://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== SCF and CCF ===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== SCF and CCF ===</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Stuart Brady discovered that how bits 3 and 5 of the flags are set after the SCF and CCF instructions actually depends on the variant of Z80 in use. On a Zilog Z80, bits 3 and 5 of the flags were set by ORing their previous values with that of A. On an NEC clone, bit 3 was unaffected, while bit 5 appears to be set by ANDing the previous value with something unknown. Previously, Ian Greenway tested this and found that bits 3 and 5 seemed simply to be copied from A, although it is not known which CPU these tests were run on. For more details, see [<del style="font-weight: bold; text-decoration: none;">http</del>://sourceforge.net/mailarchive/forum.php?thread_name=20040217082529.GH17981%40philos.lan.philosys.de&forum_name=fuse-emulator-devel here], [<del style="font-weight: bold; text-decoration: none;">http</del>://sourceforge.net/mailarchive/forum.php?thread_name=20070522223156.GA12009%40miranda.arrow&forum_name=fuse-emulator-devel here] and a more recent investigation [<del style="font-weight: bold; text-decoration: none;">http</del>://groups.google.co.uk/group/comp.sys.sinclair/msg/56dd1fd4ccb5fb3b here].</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Stuart Brady discovered that how bits 3 and 5 of the flags are set after the SCF and CCF instructions actually depends on the variant of Z80 in use. On a Zilog Z80, bits 3 and 5 of the flags were set by ORing their previous values with that of A. On an NEC clone, bit 3 was unaffected, while bit 5 appears to be set by ANDing the previous value with something unknown. Previously, Ian Greenway tested this and found that bits 3 and 5 seemed simply to be copied from A, although it is not known which CPU these tests were run on. For more details, see [<ins style="font-weight: bold; text-decoration: none;">https</ins>://sourceforge.net/mailarchive/forum.php?thread_name=20040217082529.GH17981%40philos.lan.philosys.de&forum_name=fuse-emulator-devel here], [<ins style="font-weight: bold; text-decoration: none;">https</ins>://sourceforge.net/mailarchive/forum.php?thread_name=20070522223156.GA12009%40miranda.arrow&forum_name=fuse-emulator-devel here] and a more recent investigation [<ins style="font-weight: bold; text-decoration: none;">https</ins>://groups.google.co.uk/group/comp.sys.sinclair/msg/56dd1fd4ccb5fb3b here].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Patrik Rak however later [<del style="font-weight: bold; text-decoration: none;">http</del>://www.worldofspectrum.org/forums/showthread.php?p=669314 discovered] that the way how the flags 5 and 3 are affected after SCF/CCF actually depends on the previous instruction completed. In case of genuine Zilog CPU, if an instruction modifies the flags, the immediately following SCF/CCF does move of bits 5 and 3 from A to F, whereas if an instruction doesn't modify the flags (and after interrupt), the SCF/CCF does OR of bits 5 and 3 from A to F. In case of NEC and other clones, it is similar, except that instead of OR it does AND with some unknown value, making the result unreliable.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Patrik Rak however later [<ins style="font-weight: bold; text-decoration: none;">https</ins>://www.worldofspectrum.org/forums/showthread.php?p=669314 discovered] that the way how the flags 5 and 3 are affected after SCF/CCF actually depends on the previous instruction completed. In case of genuine Zilog CPU, if an instruction modifies the flags, the immediately following SCF/CCF does move of bits 5 and 3 from A to F, whereas if an instruction doesn't modify the flags (and after interrupt), the SCF/CCF does OR of bits 5 and 3 from A to F. In case of NEC and other clones, it is similar, except that instead of OR it does AND with some unknown value, making the result unreliable.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Differences between NMOS and CMOS Z80s ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Differences between NMOS and CMOS Z80s ==</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Later, in 2004, Colin Piggot rediscovered this with his own SAM Coupé, when running a demo for SCPDU 6, coincidentally written by Simon Cooke. With the CMOS Z80, a white background colour was set over part of the screen in the demo. This was described in SAM Revival Issue 9 (March/April 2004).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Later, in 2004, Colin Piggot rediscovered this with his own SAM Coupé, when running a demo for SCPDU 6, coincidentally written by Simon Cooke. With the CMOS Z80, a white background colour was set over part of the screen in the demo. This was described in SAM Revival Issue 9 (March/April 2004).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>In 2008, this was once again [<del style="font-weight: bold; text-decoration: none;">http</del>://www.msx.org/forum/development/msx-development/bug-z80-emulation-or-tr-hw rediscovered by the MSX community].</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>In 2008, this was once again [<ins style="font-weight: bold; text-decoration: none;">https</ins>://www.msx.org/forum/development/msx-development/bug-z80-emulation-or-tr-hw rediscovered by the MSX community].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Bus ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Bus ==</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A basic Flags test program for emulators is available [http://homepage.ntlworld.com/mark.woodmass/z80tests.tap here]. Note that the program makes heavy use of ROM data during the tests and so should only be used with an unpatched copy of the original 48K ROM to obtain correct results.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>A basic Flags test program for emulators is available [http://homepage.ntlworld.com/mark.woodmass/z80tests.tap here]. Note that the program makes heavy use of ROM data during the tests and so should only be used with an unpatched copy of the original 48K ROM to obtain correct results.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Patrik Rak has written a [http://zxds.raxoft.cz/taps/misc/z80test.zip Z80 instruction tester], as [<del style="font-weight: bold; text-decoration: none;">http</del>://www.worldofspectrum.org/forums/showthread.php?t=41834 announced here].</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Patrik Rak has written a [http://zxds.raxoft.cz/taps/misc/z80test.zip Z80 instruction tester], as [<ins style="font-weight: bold; text-decoration: none;">https</ins>://www.worldofspectrum.org/forums/showthread.php?t=41834 announced here].</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Notable uses ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Notable uses ==</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1982&oldid=prevZub: Fix link to Z80 oral history2020-05-10T05:40:30Z<p>Fix link to Z80 oral history</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 05:40, 10 May 2020</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Zilog]] have released a number of variants of the Z80, and it has been second-sourced by many manufacturers, such as Mostek. In addition, there are numerous processors such as the R800 and T80 that are largely compatible with the Z80's instruction set.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Zilog]] have released a number of variants of the Z80, and it has been second-sourced by many manufacturers, such as Mostek. In addition, there are numerous processors such as the R800 and T80 that are largely compatible with the Z80's instruction set.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([<del style="font-weight: bold; text-decoration: none;">http</del>://archive.computerhistory.org/resources<del style="font-weight: bold; text-decoration: none;">/access</del>/text/Oral_History/102658073.05.01<del style="font-weight: bold; text-decoration: none;">.acc</del>.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([<ins style="font-weight: bold; text-decoration: none;">https</ins>://archive.computerhistory.org/resources/text/Oral_History<ins style="font-weight: bold; text-decoration: none;">/Zilog_Z80</ins>/102658073.05.01.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the КР1858ВМ1 in Cyrillic (KR1858VM1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[http://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the КР1858ВМ1 in Cyrillic (KR1858VM1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[http://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1776&oldid=prevPak21: /* Bits 3 and 5 of the F register */ Add some clarifications for memptr_eng.txt.2017-01-12T20:08:16Z<p><span dir="auto"><span class="autocomment">Bits 3 and 5 of the F register: </span> Add some clarifications for memptr_eng.txt.</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 20:08, 12 January 2017</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Woody has confirmed that bits 3 and 5 of the flags are copied on all BIT instructions on both a Zilog Z80 and an NEC clone (stated on the link above as being "unverified").</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Woody has confirmed that bits 3 and 5 of the flags are copied on all BIT instructions on both a Zilog Z80 and an NEC clone (stated on the link above as being "unverified").</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">==== Clarifications ====</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Some bits which aren't immediately clear from memptr_eng.txt but appear to be generally true:</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* MEMPTR is unchanged for DJNZ with B == 1 or for a conditional JR when the jump is not taken. (Note the difference with conditional JP and CALL where MEMPTR is set even if the jump isn't taken).</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* MEMPTR is set for IN <register>, (C) and OUT (C), <register> for all registers, not just A.</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">==== Clarification needed ====</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* What is the value of MEMPTR after IN A, 255? Everywhere else that the high byte of MEMPTR is set to A, there is no carry from the low byte (eg LD (nnnn), A), but memptr_eng.txt implies there is a carry in this case. Has anyone checked this case?</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== SCF and CCF ===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>=== SCF and CCF ===</div></td></tr>
</table>Pak21https://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1580&oldid=prevZub: /* Instruction set */ Swap Cyrillic and Latin names for U880D. Add a bit on the UB880D and UA880D2015-09-30T16:55:11Z<p><span dir="auto"><span class="autocomment">Instruction set: </span> Swap Cyrillic and Latin names for U880D. Add a bit on the UB880D and UA880D</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 16:55, 30 September 2015</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the <del style="font-weight: bold; text-decoration: none;">KR1858VM1 </del>in Cyrillic (<del style="font-weight: bold; text-decoration: none;">КР1858ВМ1 </del>in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[http://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the <ins style="font-weight: bold; text-decoration: none;">КР1858ВМ1 </ins>in Cyrillic (<ins style="font-weight: bold; text-decoration: none;">KR1858VM1 </ins>in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical<ins style="font-weight: bold; text-decoration: none;">. The UB880D was found in the Didaktik Gama amongst other machines, despite being only rated for operation up to 2.5 MHz. The UA880D may run at 4 MHz</ins>. A CMOS clone, the КР1858ВМ3, also existed, and this is known to handle the HALT instruction differently[http://zxpress.ru/article.php?id=2943]: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1547&oldid=prevZub: /* Instruction set */ More on the КР1858ВМ32015-09-02T02:17:51Z<p><span dir="auto"><span class="autocomment">Instruction set: </span> More on the КР1858ВМ3</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 02:17, 2 September 2015</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l11">Line 11:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the KR1858VM1 in Cyrillic (КР1858ВМ1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. A CMOS clone, the КР1858ВМ3, also existed, and this is known <del style="font-weight: bold; text-decoration: none;">not </del>to <del style="font-weight: bold; text-decoration: none;">increment </del>the <del style="font-weight: bold; text-decoration: none;">R register during a </del>HALT instruction[http://zxpress.ru/article.php?id=2943].</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the KR1858VM1 in Cyrillic (КР1858ВМ1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. A CMOS clone, the КР1858ВМ3, also existed, and this is known to <ins style="font-weight: bold; text-decoration: none;">handle </ins>the HALT instruction <ins style="font-weight: bold; text-decoration: none;">differently</ins>[http://zxpress.ru/article.php?id=2943]<ins style="font-weight: bold; text-decoration: none;">: memory is not refreshed, R register is not incremented HALT during DI is permitted (but interrupts remain disabled afterwards) and HALT is interrupted immediately (rather after a delay, before the start of the next M-cycle)</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1546&oldid=prevZub: Mention the КР1858ВМ32015-09-02T02:01:03Z<p>Mention the КР1858ВМ3</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<col class="diff-marker" />
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 02:01, 2 September 2015</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l11">Line 11:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the KR1858VM1 in Cyrillic (КР1858ВМ1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. A CMOS clone, the КР1858ВМ3, also existed.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The U880 was an East German clone of the Z80. This was also produced by Angstrem (Ангстрем) as the Т34ВМ1 in Cyrillic (T34VM1 in Latin script), which photomicrographs reveal to use the U880 die mask[http://zeptobars.ru/en/read/t34vm1-z80-angstrem-mme], and the KR1858VM1 in Cyrillic (КР1858ВМ1 in Latin script). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical. A CMOS clone, the КР1858ВМ3, also existed<ins style="font-weight: bold; text-decoration: none;">, and this is known not to increment the R register during a HALT instruction[http://zxpress.ru/article.php?id=2943]</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1469&oldid=prevZub: U880 cleanup2015-08-21T17:16:16Z<p>U880 cleanup</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:16, 21 August 2015</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[NEC]] produced an unlicensed clone of the Z80 ([http://archive.computerhistory.org/resources/access/text/Oral_History/102658073.05.01.acc.pdf Computer History Museum: Z80 oral history] page 13) through reverse engineering. It is this clone, the NEC µPD780 that is found in the majority of Spectrums, labelled as a "D780C -1".</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The <del style="font-weight: bold; text-decoration: none;">[[Wikipedia:ru:Т34ВМ1 и Т34ВГ1|КР1858ВМ1]] </del>(<del style="font-weight: bold; text-decoration: none;">link to Russian language Wikipedia</del>) <del style="font-weight: bold; text-decoration: none;">was produced </del>in <del style="font-weight: bold; text-decoration: none;">the Soviet Union, and </del>in <del style="font-weight: bold; text-decoration: none;">East Germany</del>, the [<del style="font-weight: bold; text-decoration: none;">[Wikipedia</del>:<del style="font-weight: bold; text-decoration: none;">de:U880|U880]</del>] (<del style="font-weight: bold; text-decoration: none;">link to German language Wikipedia</del>) <del style="font-weight: bold; text-decoration: none;">was manufactured</del>. These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The <ins style="font-weight: bold; text-decoration: none;">U880 was an East German clone of the Z80. This was also produced by Angstrem </ins>(<ins style="font-weight: bold; text-decoration: none;">Ангстрем</ins>) <ins style="font-weight: bold; text-decoration: none;">as the Т34ВМ1 </ins>in <ins style="font-weight: bold; text-decoration: none;">Cyrillic (T34VM1 </ins>in <ins style="font-weight: bold; text-decoration: none;">Latin script)</ins>, <ins style="font-weight: bold; text-decoration: none;">which photomicrographs reveal to use </ins>the <ins style="font-weight: bold; text-decoration: none;">U880 die mask</ins>[<ins style="font-weight: bold; text-decoration: none;">http</ins>:<ins style="font-weight: bold; text-decoration: none;">//zeptobars.ru/en/read/t34vm1-z80-angstrem-mme</ins>]<ins style="font-weight: bold; text-decoration: none;">, and the KR1858VM1 in Cyrillic </ins>(<ins style="font-weight: bold; text-decoration: none;">КР1858ВМ1 in Latin script</ins>). These differ from the Zilog Z80 in their setting of the carry flag after an OUTI operation, but are otherwise (almost?) identical<ins style="font-weight: bold; text-decoration: none;">. A CMOS clone, the КР1858ВМ3, also existed</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Contended memory ==</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Thomas Scherrer's [http://z80.info/ z80.info]: official Zilog manuals and the like</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Thomas Scherrer's [http://z80.info/ z80.info]: official Zilog manuals and the like</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Sean Young's [http://www.myquest.nl/z80undocumented/ ''The Undocumented Z80 Documented'']: undocumented features</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* Sean Young's [http://www.myquest.nl/z80undocumented/ ''The Undocumented Z80 Documented'']: undocumented features</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* [[Wikipedia:de:U880|U880]] (link to German language Wikipedia)</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* [[Wikipedia:ru:Т34ВМ1 и Т34ВГ1|Т34ВГ1]] (link to Russian language Wikipedia)</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">* [[Wikipedia:cs:T34VM1|T34VM1]] (link to Czech language Wikipedia)</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{CC-BY-SA-techwiki|Z80|Z80}}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>{{CC-BY-SA-techwiki|Z80|Z80}}</div></td></tr>
</table>Zubhttps://sinclair.wiki.zxnet.co.uk/w/index.php?title=Z80&diff=1284&oldid=prevZub: Use {{overline}}2015-05-16T00:07:33Z<p>Use {{overline}}</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 00:07, 16 May 2015</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Computers using the Z80 tended to run at a relatively high clock speed by for the time, compared to certain other processors such as the MOS 6502 and Motorola 6809. Doing so was required to achieve a decent level of performance, as on average, the Z80 required a larger number of clock cycles per instruction executed. This high clock speed would typically eliminate cycle stealing as a means of sharing video memory between the display generation hardware and the CPU, as the DRAM required to support this would need to be clocked at an even higher frequency. If a display is to be generated whilst video memory is being accessed, this leaves a choice of comparatively expensive VRAM with a dedicated read port for display generation, or a memory contention scheme where by the CPU will is halted when the display hardware requires access to video memory.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Computers using the Z80 tended to run at a relatively high clock speed by for the time, compared to certain other processors such as the MOS 6502 and Motorola 6809. Doing so was required to achieve a decent level of performance, as on average, the Z80 required a larger number of clock cycles per instruction executed. This high clock speed would typically eliminate cycle stealing as a means of sharing video memory between the display generation hardware and the CPU, as the DRAM required to support this would need to be clocked at an even higher frequency. If a display is to be generated whilst video memory is being accessed, this leaves a choice of comparatively expensive VRAM with a dedicated read port for display generation, or a memory contention scheme where by the CPU will is halted when the display hardware requires access to video memory.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The ZX Spectrum uses a memory contention scheme, but with a slight quirk — the <del style="font-weight: bold; text-decoration: none;">/</del>MREQ line that signifies whether the Z80 is performing memory access is not decoded by the ULA of the original Sinclair models (including the 128K), meaning that the CPU may be halted briefly to avoid contention whenever it places a value onto the address bus in the address range of contended memory (i.e. memory at 0x4000–0x7fff on the 48K Spectrum, and also the range between 0xc000–0xffff on a 128K when contended memory is paged in). As <del style="font-weight: bold; text-decoration: none;">/</del>MREQ is not decoded, this contention applies even when the Z80 is not accessing memory, i.e. when accessing I/O ports, when performing DRAM refresh, and when certain instructions place spurious values on the address bus for no specific purpose. This issue was later fixed by Amstrad for the Spectrum +3 and +2A/+2B, but by this time, a certain amount of software had grown to depend on the behaviour of the original Sinclair models.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The ZX Spectrum uses a memory contention scheme, but with a slight quirk — the <ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>MREQ<ins style="font-weight: bold; text-decoration: none;">}} </ins>line that signifies whether the Z80 is performing memory access is not decoded by the ULA of the original Sinclair models (including the 128K), meaning that the CPU may be halted briefly to avoid contention whenever it places a value onto the address bus in the address range of contended memory (i.e. memory at 0x4000–0x7fff on the 48K Spectrum, and also the range between 0xc000–0xffff on a 128K when contended memory is paged in). As <ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>MREQ<ins style="font-weight: bold; text-decoration: none;">}} </ins>is not decoded, this contention applies even when the Z80 is not accessing memory, i.e. when accessing I/O ports, when performing DRAM refresh, and when certain instructions place spurious values on the address bus for no specific purpose. This issue was later fixed by Amstrad for the Spectrum +3 and +2A/+2B, but by this time, a certain amount of software had grown to depend on the behaviour of the original Sinclair models.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Bits 3 and 5 of the F register ==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>== Bits 3 and 5 of the F register ==</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|'''Pin''' || '''Description'''</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|'''Pin''' || '''Description'''</div></td></tr>
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<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>MREQ || Memory Request</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>MREQ<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| Memory Request</div></td></tr>
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<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>IORQ || I/O Request</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>IORQ<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| I/O Request</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
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<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>RFSH || DRAM Refresh</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>RFSH<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| DRAM Refresh</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>M1 || Opcode Fetch Cycle</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>M1<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| Opcode Fetch Cycle</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>HALT || CPU Halted</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>HALT<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| CPU Halted</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>WAIT || CPU Wait</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>WAIT<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| CPU Wait</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>INT || Maskable Interrupt</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>INT<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| Maskable Interrupt</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>NMI || Non-Maskable Interrupt</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>NMI<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| Non-Maskable Interrupt</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>BUSRQ || Bus (DMA) request</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>BUSRQ<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| Bus (DMA) request</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|-</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>|<del style="font-weight: bold; text-decoration: none;">/</del>BUSACK || Bus (DMA) acknowledgement</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>|<ins style="font-weight: bold; text-decoration: none;">{{overline|</ins>BUSACK<ins style="font-weight: bold; text-decoration: none;">}} </ins>|| Bus (DMA) acknowledgement</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>|}</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
</table>Zub