Re: Could you make a 'new', 'better' computer from the C64 just by reprogramming the PLA?

On 11/3/21 10:55 PM, Claudio Sánchez wrote:
>> Yes, which makes it impossible for vic2 to fetch color from the 64k of
>> dram & replacing the 1k of sram with dram would require some dram
>> refresh logic.
> 
> But... the dram refresh logic is already there, isn't it? A different 
> thing would have been to have dram apart from main dram, so it would 
> have required that extra dram refresh logic as you point.
> 
> But if the color ram would had been made part of the main ram, it 
> wouldn't had needed dram refresh because that is already done by the chip.

They did that on TED. Which resulted in TED needing 2 bad lines (instead 
of one on VIC-II) per text line to make things work.

Also, that 12Bit data bus is already present on VIC in the VIC-20, I 
wouldn't be surprised if MOS took some ideas from that design.

  Gerrit