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 »

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.

First off prep the board. Where the socket is marked U34, there are 3 zero ohm resistor/links. These will need to be removed.
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 13432 times
Once the 3 zero ohm resistors are removed, use solder wick to clean up all of the holes.
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 13432 times
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.
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 13432 times
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.
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 13432 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 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...
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tfhh
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by tfhh »

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 13420 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 577 times
800XE320.zip
JEDEC file for 16V8 GAL
(438 Bytes) Downloaded 485 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 »

Cool, nice one :D

A little more complex to do, but very nice result.
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...
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by exxos »

Well done to both :bravo:
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by rubber_jonnie »

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

Looking good for over 30 years old.
Reassembled and cleaned.
Reassembled and cleaned.
IMG_20170904_165253.jpg (3.5 MiB) Viewed 13400 times
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...
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by exxos »

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*
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
redhawk668
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by redhawk668 »

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.
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: 800XLF, stock - 600XL, Ultimate 1 mb, Sophia RGB - 130XE, 320 kb, Sophia RGB

Sinclair stuff: 3x Spectrum 48KB, Clones: Harlequin, JS128, Nuvo128 and Issue3B replica.

Ultimate64, a few C64 breadbins and Pi1541 for storage.
atari030
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Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Post by atari030 »

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

Post by rubber_jonnie »

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

Post by walter_j64bit »

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