New answers tagged commodore-64
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Cost. Recall that Jack Tramel's mantra was "computers for the masses, not the classes". Going from 40-column to 80-column output requires faster memory (or tricks to work around slow memory), raising costs.
It appears that 80 column mode requires either a 2 MHz bus, which is what the C128 used, or a 1 MHz bus with the ability to latch and access ...
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Many answers here refer to the limitations of domestic TV sets (some of which has to do with the CRT phosphors / shadow mask dot pitch of a particular make and model) and the luma / chroma bandwidth limitations of the TV-standards-compatible composite color video signal, RF-modulated or not. And for a good reason — the “home computers” of the era were ...
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Color monitors and televisions have a limited horizontal resolution. Monochrome monitors are much sharper and basically have unlimited horizontal resolution. The 80 column PET uses a chip designed to drive a computer monitor rather than a television. The 80 column PET uses essentially the same chip that IBM used in the IBM PC for the Monochrome Display ...
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In all versions of the schematics from the Commodore C64/C64C Service
Manual, the D̅M̅A̅ line proceeds from the cartridge port to:
A 3k3 pullup resisistor.
A 74LS08 AND gate with BA (a VIC signal) to CPU RDY.
A 74LS08 AND gate with "system" (i.e., not CPU) AEC generating CAEC
to the CPU's AEC pin.
Thus bringing DMA low will immediately bring ...
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