Re: 250466 PCB curiousness

On 7/10/19 11:46 PM, smf wrote:
> On 07/07/2019 23:14, Pasi Lassila wrote:
> 
>> One good thing with SRAM is it fixes the VSP bug. One other thing is
>> it's still made. DRAM is all old stock. My SRAM board uses still
>> active components.
> 
> I thought just converting to SRAM didn't completely fix it & you still
> had to add logic to make it work properly.

How can you have the VSP-Bug with SRAM? The problem happens during a RAM 
access by VIC and that's always a read access. SRAM doesn't care what 
you do with the address lines during a read, it will happily supply the 
data that gets selected, but it cannot destroy any data since reading an 
SRAM cell doesn't change it.

With DRAM it's another story since DRAM destroys the memory cell 
contents on read and has to write them back at the end of the cycle. So 
if something happens with the adressing, the DRAM will destroy data.

  Gerrit