spicyjack Posted July 5, 2020 Share Posted July 5, 2020 (edited) When the "QuarterMeg XL" article by @ClausB came out in the September 1985 issue of BYTE, I had to try it on my K-Mart special Atari 800XL. For reference, here's the original BYTE magazine article: Quarter_MEG_ATARI_800XL_256kB_RAM.pdf I bought the chips mail order from a place in San Jose, bought the perf board and chip sockets from my local Radio Shack, and threw it together. After the upgrade, I explained to one of my friends what I had done, and he asked me to do the same upgrade to his 800XL. Years later, he got out of 8-bit Ataris, and he gave me all of the old hardware that he hadn't sold on Ebay. This is his 800XL which I had upgraded about 35 years ago. I remembered that I had did this upgrade to my 800XL, but I had forgotten that I did the same upgrade to his 800XL. I recently took this machine apart to document things (was the board socketed or not, how much corrosion was there on the RFI shields, etc.), and I "found" this upgrade attached to it. SURPRISE! The thing was, I used telephone hookup wire for most of my electronic projects at the time, since I had a bunch of it sitting around (my dad worked for the phone company), so I had a sneaking feeling that I had done this upgrade, but I wasn't sure. For about an hour or two, I was pretty convinced that this was my original 800XL that I somehow ended up with again as a craigslist/Ebay purchase. It was pretty spooky. But, I thought about it some more, and realized what the deal was; this was my friend's machine, and I did this mod on his 800XL after I did the mod on my 800XL. Thanks to @ClausB, his instructions were solid, and the trick about using half of an IC socket to so you don't have to solder directly onto the PIA was great, it was a clean install which uninstalled very quickly, I just had to cut one wire that I had soldered on to the board, "above" the row of RAM chips. So here you go, I'm going to remove this QuarterMeg XL upgrade from ~35 years ago. I pulled off the keyboard, and the RFI shield was still in place. The discoloration of the RFI shield most likely comes from the part of San Diego where this machine was used and stored, it's a few miles from the Pacific Ocean. I pulled the RFI shield off, and WHOA! what's that there? Close up of the perf board with the RAM refresh chips, and the ribbon cable where it plugs in to the board The pins on the PIA bent up, and the wires soldered to half of an IC socket, in order to make it easy to attach/unattach as needed. You can see the piece of electrical tape that covered the tops of the pins to protect from shorting it out against the RFI shield Starting the uninstall Close-up of the perf board, with the electrical tape attached to the bottom And here's the board post-uninstall. The 74LS153N got resocketed from the perf board back into the 800XL board. I have a chip pin straightener, so I was able to get the PIA pins back to their "normal" angle pretty easily. The machine boots fine with the 256KB RAM chips still installed, only the first 64KB would be used at this point Thanks for reading, feel free to ask me any questions. Edited July 5, 2020 by spicyjack Mentioned resocketing the 74LS153N 3 Quote Link to comment Share on other sites More sharing options...
ClausB Posted July 6, 2020 Share Posted July 6, 2020 (edited) Sad to see it go. Looks like you used the original 32K bank version, not the later 16K bank version I distributed after the article came out. BTW, the LS158 goes back in the motherboard socket, not the LS153. Edited July 6, 2020 by ClausB Quote Link to comment Share on other sites More sharing options...
spicyjack Posted July 6, 2020 Author Share Posted July 6, 2020 1 hour ago, ClausB said: Sad to see it go. Looks like you used the original 32K bank version, not the later 16K bank version I distributed after the article came out. I did what the article said; I didn't realize that you had done a 2nd version. I still have everything in my garage if I wanted to re-install it. 1 hour ago, ClausB said: BTW, the LS158 goes back in the motherboard socket, not the LS153. I powered it on it after I put it together and it booted fine, I just didn't get a photo of the right chip in the right socket, and guessed. Quote Link to comment Share on other sites More sharing options...
archeocomp Posted July 6, 2020 Share Posted July 6, 2020 (edited) 256kB 800XLE is MY Atari, workhorse. If you ever wanted to reinstall, I shared second ClausB 16kB bank version PCB on OSH park Edited July 6, 2020 by archeocomp Quote Link to comment Share on other sites More sharing options...
BillC Posted July 6, 2020 Share Posted July 6, 2020 2 hours ago, spicyjack said: I did what the article said; I didn't realize that you had done a 2nd version. I still have everything in my garage if I wanted to re-install it. Claus updated the design to use the same 16K bank size as the 130XE. Quote Link to comment Share on other sites More sharing options...
spicyjack Posted July 6, 2020 Author Share Posted July 6, 2020 25 minutes ago, archeocomp said: 256kB 800XLE is MY Atari, workhorse. If you ever wanted to reinstall, I shared second ClausB 16kB bank version PCB on OSH park Link? Quote Link to comment Share on other sites More sharing options...
spicyjack Posted July 6, 2020 Author Share Posted July 6, 2020 1 minute ago, BillC said: Claus updated the design to use the same 16K bank size as the 130XE. Link? Quote Link to comment Share on other sites More sharing options...
archeocomp Posted July 6, 2020 Share Posted July 6, 2020 https://oshpark.com/profiles/archeocomp 1 Quote Link to comment Share on other sites More sharing options...
BillC Posted July 6, 2020 Share Posted July 6, 2020 9 minutes ago, spicyjack said: Link? https://www.atariarchives.org/cfn/12/02/0084.php 1 Quote Link to comment Share on other sites More sharing options...
ClausB Posted July 6, 2020 Share Posted July 6, 2020 Quote Link to comment Share on other sites More sharing options...
spicyjack Posted July 6, 2020 Author Share Posted July 6, 2020 13 hours ago, archeocomp said: https://oshpark.com/profiles/archeocomp Thanks! Quote Link to comment Share on other sites More sharing options...
spicyjack Posted July 6, 2020 Author Share Posted July 6, 2020 13 hours ago, BillC said: https://www.atariarchives.org/cfn/12/02/0084.php Thanks! Quote Link to comment Share on other sites More sharing options...
spicyjack Posted July 6, 2020 Author Share Posted July 6, 2020 8 hours ago, ClausB said: I actually have this open in another browser tab, but I haven't made it all the way through the thread yet. Thanks for posting though! Quote Link to comment Share on other sites More sharing options...
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