+x=usr(1536) Posted February 16, 2021 Share Posted February 16, 2021 (edited) Received a nice little surprise today when I popped the RF shielding off of the 800XL I've had for the past 20 years or so and found a 256K upgrade in it that I was previously unaware of. It's welcome to stay In any event, I've been trying to figure out which upgrade was performed. It's obviously home-made, probably from instructions in a magazine - but, from what I've been able to dig up, I don't think it's one of @ClausB's upgrades, and I'm not finding anything that is an exact match for the hardware it uses. Starting off: Pretty obviously wired up on hobbyist breadboard. I've so far been unable to find a design for this upgrade that requires five ICs; every other design has topped out at four. There are no components on the back side of the breadboard, just a spiderweb of wiring. From left to right, the ICs are: Top row: 74LS158, 74LS393, 74LS153 (the numbers 1, 5, and 2 are scratched into them, respectively) Bottom Row: 74LS139, 74LS158 (scratched with 3 and 4, respectively) Moving on: ANTIC is a C012296, and has pin 8 jumpered back to the breadboard. Seems fairly normal from what I've found. Pins 12-16 are also jumpered on PIA, which also seems to be fairly standard. Here's the RAM and attachment for the breadboard. Also pretty standard; RAM is 256kx1, 150ns, Micron model number 1257-15. Note that there is no jumper running to the topmost IC, which the other upgrades seem to need. However, there are resistors attached to pins 2 & 9 of all sockets, with the exception of the bottommost one which has it between pins 3 & 9. And, finally, the bird's-eye view just for giggles. So... Does anyone know which memory upgrade this might be? I'd mainly like to know so that I have a point of reference in the future. Edited February 16, 2021 by x=usr(1536) Weird attachment / embedded image behaviour. 1 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted February 16, 2021 Share Posted February 16, 2021 Looks like it's the Quarter-Meg upgrade by @ClausB All the background info you could ever want here: Originally published with 32K banking, later revised to 16K banks to be compatible with the 130XE style banking. 2 Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted February 16, 2021 Author Share Posted February 16, 2021 23 minutes ago, Nezgar said: Looks like it's the Quarter-Meg upgrade by @ClausB I'd be more than happy to be proven wrong on this, but I don't think it's that one. Or, if it is, it's a modified version of it. That Byte article, funnily enough, was the last one I read before making this post. Differences I've noticed are that the 74LS151 and 74LS500s in Claus' circuit aren't present on the one I'm looking at; my best guess is that they were replaced by / consolidated into the 74LS153, 74LS139, and the additional 74LS158, but someone who is better at TTL ICs than I am would need to confirm. PIA also has fewer jumpers in his design (3 vs. 5), and there are a couple of other differences. Quote Link to comment Share on other sites More sharing options...
BillC Posted February 16, 2021 Share Posted February 16, 2021 15 minutes ago, x=usr(1536) said: I'd be more than happy to be proven wrong on this, but I don't think it's that one. Or, if it is, it's a modified version of it. That Byte article, funnily enough, was the last one I read before making this post. Differences I've noticed are that the 74LS151 and 74LS500s in Claus' circuit aren't present on the one I'm looking at; my best guess is that they were replaced by / consolidated into the 74LS153, 74LS139, and the additional 74LS158, but someone who is better at TTL ICs than I am would need to confirm. PIA also has fewer jumpers in his design (3 vs. 5), and there are a couple of other differences. There are 2 versions of Claus upgrade, the original used 32KB banks, it was designed before the 130XE was released. The later version was modified to use 16KB banks like the 130XE 2 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted February 16, 2021 Share Posted February 16, 2021 Ah k, maybe differences in the "130XE compatible 16KB bank revision. That parts list includes a 74LS153, 74LS139. The OP motherboard has an ANTIC CO12296 which is mentioned in the upgrade document also specifying 74LS158, 74LS393 but I don't see in the board above. Maybe for whatever reason it worked without, so the person who installed the mod didn't bother. 2 Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted February 16, 2021 Author Share Posted February 16, 2021 (edited) 1 hour ago, Nezgar said: Ah k, maybe differences in the "130XE compatible 16KB bank revision. That parts list includes a 74LS153, 74LS139. The OP motherboard has an ANTIC CO12296 which is mentioned in the upgrade document also specifying 74LS158, 74LS393 but I don't see in the board above. Maybe for whatever reason it worked without, so the person who installed the mod didn't bother. OK, I think I see what you're referring to now. When I read that thread that you linked to earlier, I missed Claus' post with the scans of the 130XE-compatible version of the upgrade. Will have to read through them more thoroughly tomorrow when I'm not nodding off at my desk, but I think you may be on to something Edited February 16, 2021 by x=usr(1536) Quote Link to comment Share on other sites More sharing options...
ClausB Posted February 16, 2021 Share Posted February 16, 2021 Yes, looks like mine. The 2nd '158 and the '393 are needed for the older version of ANTIC. 2 Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted February 16, 2021 Author Share Posted February 16, 2021 13 minutes ago, ClausB said: Yes, looks like mine. The 2nd '158 and the '393 are needed for the older version of ANTIC. Got it, and thanks. It seemed close, but I couldn't find a BOM that matched up 100% with what I was seeing, so wasn't totally certain. Quote Link to comment Share on other sites More sharing options...
Cabi~#599 Posted February 26, 2021 Share Posted February 26, 2021 Does anyone have an actual schematic for this 256K upgrade on the 800XL? I would like to do a DIY of it. Cabi~ Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted February 26, 2021 Author Share Posted February 26, 2021 1 hour ago, Cabi~#599 said: Does anyone have an actual schematic for this 256K upgrade on the 800XL? I would like to do a DIY of it. Cabi~ Here you go... 2 Quote Link to comment Share on other sites More sharing options...
archeocomp Posted February 26, 2021 Share Posted February 26, 2021 Schematics can be drawn by instructions in the posted text listing thread. You can order boards here https://oshpark.com/profiles/archeocomp/page/2 If you really want schematics of the mini board send me a PM. I have even smd version of the board 1 Quote Link to comment Share on other sites More sharing options...
Cabi~#599 Posted February 27, 2021 Share Posted February 27, 2021 (edited) OUTSTANDING!!! Thanks for the help on the 256K upgrade schematic! I also just discovered Claus' article in HOMEBREW magazine? http://blog.3b2.sk/igi/file.axd?file=2017%2f4%2fQuarter_MEG_ATARI_800XL_256kB_RAM.pdf Cabi~ Edited February 27, 2021 by Cabi~#599 Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted February 27, 2021 Author Share Posted February 27, 2021 17 minutes ago, Cabi~#599 said: OUTSTANDING!!! Thanks for the help on the 256K upgrade schematic! I also just discovered Claus' article in HOMEBREW magazine? http://blog.3b2.sk/igi/file.axd?file=2017%2f4%2fQuarter_MEG_ATARI_800XL_256kB_RAM.pdf Cabi~ No worries. Just make sure to build the version that uses XE-style (16K) banking; his comments about that are further up this thread. 1 Quote Link to comment Share on other sites More sharing options...
+Peter Rabitt Posted May 12, 2021 Share Posted May 12, 2021 (edited) Hi All with 800xl and the 256kb upgrade... I also have the same upgrade and was wondering Two things. 1. how to tell if the upgrade is for the 32k banks or the 16k banks, something tells me I have the one with 32k banks because it was used as ram disk on my BBS in 1980-1989.(Or so) The computer does not come up but that maybe because it is tied to the ATR 8000 and other things that may have controlled it( software, dos, etc). I also have a few other wires that seem to also be related to the upgrade, 1 etch to a pin of the 41256(all 8 of them) are cut on the bottom of the board, a push buten switch, different wires running around and a resistor running to the S-Video plug. I do have pictures and can add them if maybe some one can figure this out. Here is the overall picture.. Yea under the 800xl is a 400 I am also working with. I has a mosaic 64k board that I am trying to figure out also.. It seems I did a lot of mods. back in the day LOL now I can't even find the paper work.!!! Edited May 12, 2021 by Peter Rabitt Missspelled words etc 1 Quote Link to comment Share on other sites More sharing options...
BillC Posted May 12, 2021 Share Posted May 12, 2021 17 minutes ago, Peter Rabitt said: 1 etch to a pin of the 41256(all 8 of them) are cut on the bottom of the board, This trace grounds pin 1, unused on the 4164 but an additional address signal on the 41256, if left intact only the first 64K of the 41256 would be usable. Quote Link to comment Share on other sites More sharing options...
+Peter Rabitt Posted May 12, 2021 Share Posted May 12, 2021 Thank you I should have guessed that as I have read some to the info on the upgrade. Also there is a 100 Ohm resistor there also on the top of the board. Well one answer down many more to go... Quote Link to comment Share on other sites More sharing options...
BillC Posted May 12, 2021 Share Posted May 12, 2021 5 hours ago, Peter Rabitt said: Also there is a 100 Ohm resistor there also on the top of the board. If it's leading to pin 5 of the monitor port this is to connect the chroma signal, which is missing on the 800XL. Quote Link to comment Share on other sites More sharing options...
ClausB Posted May 13, 2021 Share Posted May 13, 2021 I can't see which chips are on your perf board there, but I see 5 wires to the PIA, which implies the later, 16K bank mod. The earlier, 32K mod had only 3 wires. 2 Quote Link to comment Share on other sites More sharing options...
manterola Posted May 13, 2021 Share Posted May 13, 2021 (edited) On 2/26/2021 at 4:50 PM, archeocomp said: Schematics can be drawn by instructions in the posted text listing thread. You can order boards here https://oshpark.com/profiles/archeocomp/page/2 If you really want schematics of the mini board send me a PM. I have even smd version of the board Hi @Cabi~#599, where are you located? I have an spare PCB from oshpark for this RAM upgrade available. If you are in USA, I can put it in an envelope for you. Edit: actually if you are not in USA I can also put it an envelope. I was able to send an small pcb to Belgium that way last month. Edited May 13, 2021 by manterola Quote Link to comment Share on other sites More sharing options...
+Peter Rabitt Posted May 13, 2021 Share Posted May 13, 2021 Hi all!!! Thanks for all the comments, I am checking the schematics and find that the wires(some of them) do go to the right places... I do see a problem and I have not tried to look into it yet because I do not have my soldering tool working yet. Also the vector board the ckt is on is cracked and I have to slowly pry it up from the double sided tape it was mounted to...Maybe I will look into the PCB that has this ckt on it. ONLY $8.00 I do not understand the wire from the 5v at R32 to a push button switch does?? It goes to the "Pcb" the ckt is on but I have not traced it out yet because of the above problem. I do need to get the 800xl running.It is not booting up.. the video rolls and not info on it. when I hit "reset" it stops and just becomes a blank screen. I am using the s-video with the mod. for chroma to pin 5. Is it possible that I need to boot something to get the 800xl to settle down an run something.. Maybe a dos disk or a modified dos disk??? Still looking for my old BBS program to see if I loaded a extra program to get it going... Quote Link to comment Share on other sites More sharing options...
+Peter Rabitt Posted May 16, 2021 Share Posted May 16, 2021 Hi ALL... Well I have ordered the PCB from OSH PARK and will get it in about a week or so.. the vector board is broken in half and has a other ckt attached to it. The circut looks like one IC, appears to be a 16 pin but the double sided tape I used has not let me see the name. It looks like one part of the chip is used.(only pins on one side are wired. plus pwr and gnd.) It ties a 5V signal thru a push button switch to the pin 11 of the GTIA chip. The pin 11 is lifted from the socket and it gets it signal from the chip. See the picture above. There does not appear, as of yet, that any other sig. goes to the chip. Quote Link to comment Share on other sites More sharing options...
+x=usr(1536) Posted May 16, 2021 Author Share Posted May 16, 2021 On 5/12/2021 at 12:50 PM, Peter Rabitt said: Hi All with 800xl and the 256kb upgrade... I also have the same upgrade and was wondering Two things. 1. how to tell if the upgrade is for the 32k banks or the 16k banks, something tells me I have the one with 32k banks because it was used as ram disk on my BBS in 1980-1989.(Or so) Grab a copy of eXtended RAM Test 0.22.0 and run it. If it reports 15 banks of RAM, you have 16K banking. If it reports only 7, you have 32K banking. Note that I've never run it on a machine with 32K banking, but it seems reasonable that this is how it would report. The manual is here, BTW. On 5/12/2021 at 12:50 PM, Peter Rabitt said: The computer does not come up but that maybe because it is tied to the ATR 8000 and other things that may have controlled it( software, dos, etc). It should at least boot to BASIC. Is that not happening? Quote Link to comment Share on other sites More sharing options...
+Peter Rabitt Posted May 16, 2021 Share Posted May 16, 2021 Good day, x=usr(1536) Well the computer did come up but with a dos cartage or with out it just rolled, kinda like tv's did with no sync, no basic was seen but it was rolling so not much could be seen. After I get the new PCB and check all the connections I will be able to tell more. The roll was seen before I took the covers off and found the memory update.. I will add more after I get a stable 800xl w/256k mem. Thanks for the file location as I have downloaded and will try it out on my 400 w/mosaic 64k upgrade that does not show extra mem. with spartados X cartage. 1 Quote Link to comment Share on other sites More sharing options...
+Peter Rabitt Posted June 6, 2021 Share Posted June 6, 2021 I am haveing a problem or question...While looking into the changes to my 800xl I found a extra set or wires what I have no idea about.It looks like a push button switch was added to the Pin 11 of the GTIA chip. There is a chip between the pin 11 sig and the signal coming from the mother board. It appears the have an Quad 2 Input exclusive OR gate in line with the signal. So to be more informative the switch has +5.0 volt and it ties to one input of the OR gate and the other input is from the mother board. I think the signal from where ever it comes from(?). The input from the switch has a 1k pulldown so the pin looks low until you push the switch. I know trying to explain is hard...If i had more time in CAD i would draw it up.(a picture is worth a 1000 words). This was the bbs computer and i think it had something to do with the BBS, but as time is slowing me down I can not remember what it did.. Also some mesg. on the outside of the computer said abot 1= ger,2=atari etc... O well back to the switch... Peter Quote Link to comment Share on other sites More sharing options...
+David_P Posted June 7, 2021 Share Posted June 7, 2021 GTIA pin 11 is TRIG 3. That's GINTLK - sounds like it may be a homemade tool to softload ROM images. Quote Link to comment Share on other sites More sharing options...
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