exxos's Atari, Amiga & retro forum

Trollbra wrote: 19 Dec 2020 14:42
if i'm sure RAM/MMU are the problem, why not... What expansion do you advise ?

Personally my preferred RAM expansion is the Ultimate 1MB, as it gives you many options for different RAM configurations.

I have heard it said that it is not 100% compatible, but I haven't yet encountered anything that won't run on it, plus if you also have a SIDE, SIDE2, SIDE3 cartridge it gives you an extremely complete hard drive and cartridge/ATR/XEX solution.

As for SIO Max, if you power it off the Atari, selection of files from the boot up Atari menu is best, rather than the built in screen on the SIO Max.

Try to remove EMMU and cross-wire its socket, so the computer would behave as it had only 64 kB of RAM, and if it doesn't help, try to substitute MMU with another one or a GAL replacement (in 800 XL it was a PAL chip, so GAL replacement is 100% compatible).

tzok wrote: 20 Dec 2020 12:34 Try to remove EMMU and cross-wire its socket, so the computer would behave as it had only 64 kB of RAM, and if it doesn't help, try to substitute MMU with another one or a GAL replacement (in 800 XL it was a PAL chip, so GAL replacement is 100% compatible).

EMMU_64k.png

Ok I try this, thanks ! No need to replace original resistor ?

These "resistors" mounted instead of EMMU are just jumpers (0 Ohm).

tzok wrote: 21 Dec 2020 14:18 These "resistors" mounted instead of EMMU are just jumpers (0 Ohm).

I want to be sure I have understood correctly before starting, in first (step 1) I remove MMU and cross-wire its socket like your screenshot. If that doesn't work I replace MMU (I own 800XL MMU) without modify step 1, that's right ?

Not MMU, but EMMU. This is how 130XE (ECI) boards were configured for 65XE/800XE computers.

You could also replace the MMU, with another one or a programmed GAL replacement.

I replaced MMU and cross-wire its socket (64k native mode) like your screenshot, the same ! :?
What can I try now ?

I don't know if it helps but the 6502 is hot !

Have you tested base RAM with something more than a SELF-TEST? MT chips are known to go bad.

Interesting - you have 3 different types of capacitors in RAM BANK 1, and some sockets are rotated by 180°.

Sally (6502C) normally gets quite hot, but it also gets damaged quite often, worth to check.

tzok wrote: 23 Dec 2020 14:06 Have you tested base RAM with something more than a SELF-TEST? MT chips are known to go bad.

Yes, I have the Jurgen's Sys-Check cartridge !

tzok wrote: 23 Dec 2020 14:06 Interesting - you have 3 different types of capacitors in RAM BANK 1, and some sockets are rotated by 180°.

Some sockets are rotated by 180° ? I don't understand !?

tzok wrote: 23 Dec 2020 14:06 Sally (6502C) normally gets quite hot, but it also gets damaged quite often, worth to check.

I have already tried to replace it with another, it's the same...