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Z80: Difference between revisions
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[[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". | [[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". | ||
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[ | 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[https://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). | ||
== Contended memory == | == Contended memory == | ||
