A little bit of 8 Bit: 65XE upgrade to 128k RAM

Any 8bit repairs, images, cool things, upgrades etc.
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rubber_jonnie
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by rubber_jonnie »

Trollbra wrote: Sat Dec 19, 2020 2:42 pm
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.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
tzok
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by tzok »

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
EMMU_64k.png (212.64 KiB) Viewed 4083 times
Trollbra
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by Trollbra »

tzok wrote: Sun Dec 20, 2020 12:34 pm 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 ?
tzok
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by tzok »

These "resistors" mounted instead of EMMU are just jumpers (0 Ohm).
Trollbra
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Joined: Fri Dec 18, 2020 9:31 pm

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by Trollbra »

tzok wrote: Mon Dec 21, 2020 2:18 pm 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 ?
tzok
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by tzok »

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.
Trollbra
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by Trollbra »

I replaced MMU and cross-wire its socket (64k native mode) like your screenshot, the same ! :?
P1060061.JPG
P1060061.JPG (500.48 KiB) Viewed 3999 times
What can I try now ?
Trollbra
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Joined: Fri Dec 18, 2020 9:31 pm

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by Trollbra »

I don't know if it helps but the 6502 is hot !
tzok
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by tzok »

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.
Trollbra
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Joined: Fri Dec 18, 2020 9:31 pm

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by Trollbra »

tzok wrote: Wed Dec 23, 2020 2:06 pm 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: Wed Dec 23, 2020 2:06 pm 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: Wed Dec 23, 2020 2:06 pm 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...
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