VICMem

[brain]

I know I may seem persistent on this but a comment from Skoe made me realise a very fast SRAM chip could cause ringing on the databus.

It very well may do that, but the databus is less concerning on ringing than the address bus, because it's only a concern on reads, and the bus is not latched until the falling edge of the clock on reads, which will be long after the ringing occurs.

Jim

[eslapion]

@Brain
True

[brain]

Hi Brain,
but if I remember well the right signal to drive the /WRITE pin of the RAM is VRW (PIN 17 on cartridge connector) and not the CRW (PIN 18 on cartridge connector).

Is it relevant?

Yes, it is, and I have updated the design. I'll put the new one out on my web site.

Jim

[brain]

http://go4retro.com/downloads/VICMem/VICMem_1.0.zip

[Kakemoms]

Hi Brain,
but if I remember well the right signal to drive the /WRITE pin of the RAM is VRW (PIN 17 on cartridge connector) and not the CRW (PIN 18 on cartridge connector).

Is it relevant?

Yes, it is, and I have updated the design. I'll put the new one out on my web site.

Jim

The only difference being that VRW is driven high by the 6560/1 in the second half of the clock. Using VRE could (in teory that is) prevent proper writing if your memory is very fast, but othervise both should work.

For ringing problems I found that resistors (pull-down) seem to clean things up a little.