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

Post by rubber_jonnie » Thu Aug 31, 2017 12:40 am

Hoping nobody minds, especially since we are predominantly 16 Bit, but having just completed a successful upgrade of my 65XE from 64k to 128k, I know how difficult it was to source the parts, so I wanted to share with everybody.

The parts needed are:

1x 20 pin DIL socket for the MMU chip
8x 16 pin DIL socket for the RAM chips
8x 1uF ceramic capacitors
1x Atari C25953 MMU (Search eBay for "NEW Atari computer 16 DIP IC 130XE 65XE 65 130 XE C25953-20 EMMU memory IC chip")
8x RAM chips (Search eBay for "8x MB8264A-15, 64Kx1-bit NMOS Dynamic RAM-NEW", a guy in Bulgaria is selling and has some left)

Your 65XE will need to be one that has the slots free for the additional memory, or this won't work.

IMG_20170807_213028.jpg
First off prep the board. Where the socket is marked U34, there are 3 zero ohm resistor/links. These will need to be removed.
IMG_20170807_213028.jpg (3.74 MiB) Viewed 944 times
IMG_20170809_214647.jpg
Once the 3 zero ohm resistors are removed, use solder wick to clean up all of the holes.
IMG_20170809_214647.jpg (4.47 MiB) Viewed 944 times
IMG_20170809_220209.jpg
Solder in all the capacitors, followed by the 8x 16 pin sockets in slots U26 to U33, and the 1x 20 pin socket in the slot marked U34.
IMG_20170809_220209.jpg (4.31 MiB) Viewed 944 times
IMG_20170809_223335.jpg
Finally, plug in all of the RAM chips into U26 to U33, and the C25953 MMU into U34. Make sure the C25953 is located to the left of the 20 pin socket when looking from the front of the mainboard, and as in the picture.
IMG_20170809_223335.jpg (4.07 MiB) Viewed 944 times
Once completed, find a 128k demo, such as the Space Harrier Demo (This is really cool!), and if everything is ok, then your 128k software will run.

Mine worked first time, but if it doesn't work for you, I suggest a magnifying glass to make sure there are no solder whiskers bridging pads, and that all the chips are nicely seated.

If it doesn't work first time, provided you've used sockets, then you can remove the chips and check it's all good without.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

tfhh
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Joined: Sat Aug 26, 2017 5:31 pm

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

Post by tfhh » Thu Aug 31, 2017 12:26 pm

Hi,
rubber_jonnie wrote:
Thu Aug 31, 2017 12:40 am
Hoping nobody minds, especially since we are predominantly 16 Bit, but having just completed a successful upgrade of my 65XE from 64k to 128k, I know how difficult it was to source the parts, I wanted to share with everybody.
Nice solution - well done! :goodpost:

If you want... I make another solution - cheaper and same effort, but you will get 320 KB RAM :)

You need:
8x 41256 DRAMs
1x resistor 33 Ohm
1x GAL 16V8 DIP
1x 74LS95

Insert the 8 DRAMs (you can get them cheap on eBay or you buy an Amiga 500 memory expansion for less then 10 USD/Pound/Euros which contains such DRAMs often and rip off the chips). Bent pin 1´s of the 8 DRAMs up OR connect unused pads for pin 1 of the sockets. You don´t need the CO25953, the GAL will do this job.

img6F.jpg
img6F.jpg (857.22 KiB) Viewed 932 times

Here´s the GAL source listing:

Code: Select all

CHIP    XE_320k    GAL16V8    SIMPLE_MODE

A14    A15   pb2   pb3      pb4      cas     pb6    pb7  mode  GND
mhalt  ra8   map   casbank  casmain  fa_14   fa_15  pb5  phi2  VCC

 fa_15        = A15
              + A14 & pb3 & /pb4 & mode & mhalt
              + A14 & pb3 & /pb5 & mode & /mhalt;

 /fa_14       = /A14
              + /A15 & /pb2 & /pb4 & mode & mhalt
              + /A15 & /pb2 & /pb5 & mode & /mhalt;

 casmain      = /phi2
              + cas
              + /A15 & A14 & /pb4 & mode & mhalt
              + /A15 & A14 & /pb5 & mode & /mhalt;

 /casbank     = /A15 & A14 & phi2 & /pb4 & /cas & mode & mhalt
              + /A15 & A14 & phi2 & /pb5 & /cas & mode & /mhalt;

 /map         = pb4 & pb5 & /pb7;

 ra8          = /phi2 & pb6 & mode
              + phi2 & pb7 & mode;
The LS7495 must be placed at the positon of U35. The GAL - bent pin 7, 8, 9,12 and 13 up - will be placed in U34. Connect pin 7 of the GAL to pin 16 of PIA and pin 8 of the GAL to pin 17 of PIA. Pin 9 can be left open (expansion enabled) or closed by switch to ground to disabled the expansion. Pin 12 via 33 Ohm resistor to the pin 1´s of the 8 DRAMs (memory addressline A8) and pin 13 to the pin 6 of MMU. This pin must be also bended, so better is to desolder the MMU, fit it into a socket and replace it with pin 6 bend up.

I make several years ago an article for the ABBUC magazine no. 95. You can download it here, but the text is only in german - sorry.

Jurgen
Attachments
320 KB for Atari XE.zip
German article with pictures of ABBUC magazine 95
(916.2 KiB) Downloaded 21 times
800XE320.zip
JEDEC file for 16V8 GAL
(438 Bytes) Downloaded 21 times

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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 » Thu Aug 31, 2017 4:07 pm

Cool, nice one :D

A little more complex to do, but very nice result.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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

Post by exxos » Thu Aug 31, 2017 4:46 pm

Well done to both :bravo:
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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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 » Mon Sep 04, 2017 5:22 pm

Here is the finished article, reassembled post 128k upgrade and with a case and keyboard clean.

Looking good for over 30 years old.
IMG_20170904_165253.jpg
Reassembled and cleaned.
IMG_20170904_165253.jpg (3.5 MiB) Viewed 912 times
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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exxos
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Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by exxos » Mon Sep 04, 2017 5:40 pm

rubber_jonnie wrote:
Mon Sep 04, 2017 5:22 pm
Here is the finished article, reassembled post 128k upgrade and with a case and keyboard clean.

Looking good for over 30 years old.
*envy mode on*
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

redhawk668
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Joined: Sat Jan 06, 2018 3:03 pm
Location: Netherlands

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

Post by redhawk668 » Fri Feb 23, 2018 6:30 pm

I’ve done a 320 kb upgrade on a 130XE, I had to desolder the second bank of ram chips. My solution uses a 74LS158, a 33 ohm resistor and some wire. I used the 256 kb drams from a dead Atari ST.
Total retro nut, my collection: 1040 STE, TOS 2.06, 4 mb, CosmosEx - 520 STFM, TOS 1.04, 4 mb, Blitter, CosmosEx - 520 STFM, TOS 1.04, 4 mb - 1040 STF, TOS 1.04, 1 mb, Gotek - Amiga 1200 with Blizzard 1220/4 - Amiga 500 + ACA500 - Amiga 500 + TF530, 1 mb chipram hack.

Atari 8 bit: 800XL, stock - 600XL, Ultimate 1 mb, Sophia RGB - 130XE, 320 kb, Sophia RGB

Sinclair stuff: ZX Spectrum Plus - ZX Spectrum 48 kb and self built clones.

atari030
Posts: 38
Joined: Mon Feb 12, 2018 12:43 pm

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

Post by atari030 » Sat Feb 24, 2018 6:39 am

Nice to see some 130XE love. Mine is sitting between a A1200 and a Falcon and I have one more to fix. When I got my 800XL the 130XE popped along not long after and I would go all giddy looking at photos of it, same as I did for the Falcon. Say what you will, Jack Tramiel new styling.

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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 » Sat Feb 24, 2018 10:49 am

redhawk668 wrote:
Fri Feb 23, 2018 6:30 pm
I’ve done a 320 kb upgrade on a 130XE, I had to desolder the second bank of ram chips. My solution uses a 74LS158, a 33 ohm resistor and some wire. I used the 256 kb drams from a dead Atari ST.
Any chance of some pics and details?
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

walter_j64bit
Posts: 20
Joined: Thu Mar 22, 2018 1:34 am

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

Post by walter_j64bit » Thu Mar 22, 2018 2:20 am

A 65XE to 128k nice work! I would love to see 65XE to 256K. 8-)

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