Re- RAM 512KSRAM extension module for Atari 65-130XE and 800

Hi Mathy,

I'll try to adopt 1MB SRAM but I need to know how you solved memory bank's decoding. Are you using some CPLD or separately ICs to do that? I found your 1MB upgrade using SIMM DRAM module but decoding way you're using is little bit strange for me :-)

One more question. Is your RAM upgrade mod compatible with e.g. U1M?

Regards, pancio

https://abbuc.de/forum/viewtopic.php?p=1466#p1466

Mathy schrieb: Hello pancio

My upgrade uses port B bits 0, 1, 2, 3, 6 and 7. If port B pins 4 and 5 are high, bits 0, 1, 6 and 7 work as usual. If either bit 4 or bit 5 or both go(es) low, the status of BASIC, OS ROM/RAM, Selftest and Missile Command (XEGS only) is frozen and bits 0, 1, 6 and 7 only control expanded RAM (as do bits 2 and 3).

Sincerely

Mathy

Hello pancio

I don't know how the U1MB works, so I can not tell you anything about the compatibility to my 1MB upgrade.

What exactly do you mean by "memory bank's decoding"?

Sincerely

Mathy

Hi Mathy,

I'm not wondering about U1M but it's something like commercial standard for rich people :-) But I suppose that both mods should be compatible using PIA PORTB bits area to avoid problems with software.

Regarding your mod, I will drop eye on the truth table to build functions for CPLD. That's all.

Regards, Blazej