NTSC Spectrum: Difference between revisions
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One example of an NTSC Spectrum | The '''NTSC Spectrum''' was sold in Chile. It was not sold in the USA as it did not meet FCC regulations<ref>The ZX Spectrum ULA, Chris Smith, 2010, p. 252</ref>. Instead, the [[Timex 2000 series|TS2068]] was produced. | ||
One example of an NTSC Spectrum has been found in Chile. As far as is known, it is the same as a normal (PAL) Spectrum with the following differences: | |||
* The CPU is clocked at 3.5275 MHz | * The CPU is clocked at 3.5275 MHz | ||
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Many thanks to Claudio Bernet for running all the tests on his machine. Three photos are available: [http://img.photobucket.com/albums/v400/zxspectrum/SSA40755.jpg 1], [http://img.photobucket.com/albums/v400/zxspectrum/SSA40764.jpg 2], [http://img.photobucket.com/albums/v400/zxspectrum/SSA40769.jpg 3]. | Many thanks to Claudio Bernet for running all the tests on his machine. Three photos are available: [http://img.photobucket.com/albums/v400/zxspectrum/SSA40755.jpg 1], [http://img.photobucket.com/albums/v400/zxspectrum/SSA40764.jpg 2], [http://img.photobucket.com/albums/v400/zxspectrum/SSA40769.jpg 3]. | ||
Another NTSC Spectrum has been found by Richard Atkinson, containing a 5C114E ULA, dated 8248[http://worldofspectrum.org/forums/showthread.php?p=763629]. | |||
Although the clock rate is slightly higher, any software making heavy use of the lower 16 KB of RAM will run slower on the NTSC Spectrum, since the proportion of time during which memory is contended is greater. This is a result of the NTSC Spectrum's need to render the display at a higher frame rate (60 Hz instead of 50 Hz). | |||
== References == | |||
<references/> | |||
{{CC-BY-SA-techwiki|NTSC Spectrum|NTSC_Spectrum}} | {{CC-BY-SA-techwiki|NTSC Spectrum|NTSC_Spectrum}} | ||
Revision as of 01:50, 14 April 2014
The NTSC Spectrum was sold in Chile. It was not sold in the USA as it did not meet FCC regulations[1]. Instead, the TS2068 was produced.
One example of an NTSC Spectrum has been found in Chile. As far as is known, it is the same as a normal (PAL) Spectrum with the following differences:
- The CPU is clocked at 3.5275 MHz
- The ULA is a model 6C011E-3 which generates a NTSC frame size and rate
- One frame lasts 0xe700 (59136) tstates, giving a frame rate of 3.5275×106 / 59136 = 59.65 Hz
- 224 tstates per line implies 264 lines per frame.
- The first contended cycle is at 0x22ff (8959). This implies 40 lines of upper border, 192 lines of picture and 32 lines of lower border/retrace.
- The contention pattern is confirmed as being the same 6,5,4,3,2,1,0,0 as on the 48K machine.
Many thanks to Claudio Bernet for running all the tests on his machine. Three photos are available: 1, 2, 3.
Another NTSC Spectrum has been found by Richard Atkinson, containing a 5C114E ULA, dated 8248[1].
Although the clock rate is slightly higher, any software making heavy use of the lower 16 KB of RAM will run slower on the NTSC Spectrum, since the proportion of time during which memory is contended is greater. This is a result of the NTSC Spectrum's need to render the display at a higher frame rate (60 Hz instead of 50 Hz).
References
- ↑ The ZX Spectrum ULA, Chris Smith, 2010, p. 252
Article license information
This article uses material from the "NTSC Spectrum" article on the ZX Spectrum technical information wiki at Fandom (formerly Wikia) and is released under the Creative Commons Attribution-Share Alike License.