+af0l Posted January 24, 2023 Share Posted January 24, 2023 I have recently picked up an Atari 800xl. It seem to have a memory upgrade installed, but it makes me wonder. The chips look that they should be 256k, but the memory tests only show 192k. I have tried to identify the make but failed miserably. Comparing the installation to other upgrades raises further questions - what is the function of pin 9 in the PIA that is connected to the board? Sally's pin 35 is supposed to be N.C., too. If anyone knows this design, I'd be very grateful for the info. Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted January 24, 2023 Share Posted January 24, 2023 (edited) 4 PIA port B bits used (PB2, PB3, PB6 and PB7) so it should be 16 banks, not 8, which should result in +256KB. Check soldering carefully, maybe a wire is loose somewhere. The pin 9 on PIA is port A bit 7 (PA7), which is - for instance - 2nd joystick right direction. I guess, pushing a joystick in this direction at startup disables... something. Maybe the whole expansion, maybe half of it. could you give it a try? Sally's pin 35 is /HALT, a very important chip. It is connected to an expansion since it's a compy-shop type. It wouldnt be connected if it was a rambo type. Edited January 24, 2023 by Peri Noid 1 Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted January 24, 2023 Share Posted January 24, 2023 Maybe it replaces 64k (base) RAM with 256k RAM, so you end up with 64k base RAM and 192k XRAM. 3 Quote Link to comment Share on other sites More sharing options...
+tf_hh Posted January 25, 2023 Share Posted January 25, 2023 9 hours ago, af0l said: I have recently picked up an Atari 800xl. It seem to have a memory upgrade installed, but it makes me wonder. The chips look that they should be 256k, but the memory tests only show 192k. I have tried to identify the make but failed miserably. Comparing the installation to other upgrades raises further questions - what is the function of pin 9 in the PIA that is connected to the board? Sally's pin 35 is supposed to be N.C., too. If anyone knows this design, I'd be very grateful for the info. This looks like the Atari-Magazin RAM expansion. It uses 8 pieces of 41256 DRAMs instead the installed 4164 ones. You get 64 KB base memory and 192 KB expanded memory. This expansion supports CPU, ANTIC and both access like the 130 XE or also called "Compy-Shop" mode. The SimCheck software seems to be not able to detect this kind of memory size, just try XRAM or others. Pin 35 of a Sally CPU (! - not the standard 6502) is the HALT signal, which is needed for seperate ANTIC vs. CPU access. Pin 8 (not 9!) of ANTIC is REF (Refresh). This expansion regards the need of more refresh cycles for 41256 DRAM and suppprts the older ANTIC "D" with 7-bit refresh, many others do this not in the 80s, so memory problems occur. It´s - for this time - a very good design. 2 1 Quote Link to comment Share on other sites More sharing options...
+af0l Posted January 25, 2023 Author Share Posted January 25, 2023 48 minutes ago, tf_hh said: This looks like the Atari-Magazin RAM expansion. It uses 8 pieces of 41256 DRAMs instead the installed 4164 ones. You get 64 KB base memory and 192 KB expanded memory. This expansion supports CPU, ANTIC and both access like the 130 XE or also called "Compy-Shop" mode. The SimCheck software seems to be not able to detect this kind of memory size, just try XRAM or others. Pin 35 of a Sally CPU (! - not the standard 6502) is the HALT signal, which is needed for seperate ANTIC vs. CPU access. Pin 8 (not 9!) of ANTIC is REF (Refresh). This expansion regards the need of more refresh cycles for 41256 DRAM and suppprts the older ANTIC "D" with 7-bit refresh, many others do this not in the 80s, so memory problems occur. It´s - for this time - a very good design. Wow, thank you all for the input! @Peri Noid I will give it a try with the joystick tonight, sure! @tf_hh Great explanation! It is connected to the pin 8 of the ANTIC, correct. I noticed the 74LS939, and deduced that it implements a counter for refresh. So the next goals are to find info about the Atari-Magazin expansion and another test program, which may produce different results. Quote Link to comment Share on other sites More sharing options...
+tf_hh Posted January 25, 2023 Share Posted January 25, 2023 6 hours ago, af0l said: @Peri Noid I will give it a try with the joystick tonight, sure! Nothing will happen, because he was wrong with the chip. It´s the ANTIC, not the PIA. Quote Link to comment Share on other sites More sharing options...
Peri Noid Posted January 25, 2023 Share Posted January 25, 2023 (edited) 2 hours ago, tf_hh said: Nothing will happen, because he was wrong with the chip. It´s the ANTIC, not the PIA. No, you are wrong here. There's a wire going to PIA pin 9 (a purple one) - look at the first picture. Edited January 25, 2023 by Peri Noid 1 Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted January 25, 2023 Share Posted January 25, 2023 Is it me or is there no ram chips on that upgrade? All 74 series Quote Link to comment Share on other sites More sharing options...
+tf_hh Posted January 25, 2023 Share Posted January 25, 2023 1 hour ago, Peri Noid said: No, you are wrong here. There's a wire going to PIA pin 9 (a purple one) - look at the first picture. Ah, well, overlooked. Sorry. But for that this signal is used... strange. 1 Quote Link to comment Share on other sites More sharing options...
+af0l Posted January 25, 2023 Author Share Posted January 25, 2023 4 hours ago, Mclaneinc said: Is it me or is there no ram chips on that upgrade? All 74 series Sure. But the chips on the main board are replaced (8x256kbit) Quote Link to comment Share on other sites More sharing options...
marcokitt2000 Posted January 25, 2023 Share Posted January 25, 2023 21 hours ago, af0l said: I have recently picked up an Atari 800xl. It seem to have a memory upgrade installed, but it makes me wonder. The chips look that they should be 256k, but the memory tests only show 192k. I have tried to identify the make but failed miserably. Comparing the installation to other upgrades raises further questions - what is the function of pin 9 in the PIA that is connected to the board? Sally's pin 35 is supposed to be N.C., too. If anyone knows this design, I'd be very grateful for the info. Thats a nice Dutch product made in Holland JM 86. Maybe John Marris from atari pokey (ANG). Gr. Marco 1 Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted January 26, 2023 Share Posted January 26, 2023 15 hours ago, af0l said: Sure. But the chips on the main board are replaced (8x256kbit) Ah, could not see them / didn't notice them.. Thanks.. Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted January 27, 2023 Share Posted January 27, 2023 On 1/25/2023 at 9:05 AM, tf_hh said: This looks like the Atari-Magazin RAM expansion. It uses 8 pieces of 41256 DRAMs instead the installed 4164 ones. You get 64 KB base memory and 192 KB expanded memory. This expansion supports CPU, ANTIC and both access like the 130 XE or also called "Compy-Shop" mode. The SimCheck software seems to be not able to detect this kind of memory size, just try XRAM or others. Sorry, but that sounds very strange (or completely wrong) to me... Afaik, the german Atari Magazin RAM upgrade does NOT replace 64k RAM with 256k RAM, instead it adds 256k RAM to the base 64k RAM giving a total of 320k RAM. The german Atari Magazin upgrade was/is Rambo, TOMS, Newell, Peterson, ... compatible using blocks 8ACE and NOT Compyshop compatible (which uses blocks 26AE). Or am I completely wrong ?!? http://www.b-pahl.de/atari8bit/RAM-Disk/ram-disk.html The PCB says "made in Holland, JM 86" and the Atari Magazin RAM upgrade was from someone in Germany and not made in Holland. And not 1986 afaik. BUT - there was also a dutch Atari Magazine (by Stichting Atari Gebruikers, SAG), so maybe maybe it was from this magazine ?!? I thought the pcb above could be a RAM upgrade from SAG or another dutch club. Someone should give it to Mathy, he will immediately change the PCB so it no longer says "made in Holland"... Attached a scan of the german Atari Magazin article, that even has "320KByte" in the title... (320KByte do-it-yourself) and somewhere in the text it says Rambo compatible... 1 Quote Link to comment Share on other sites More sharing options...
+CharlieChaplin Posted January 27, 2023 Share Posted January 27, 2023 Think I read somewhere about an SAG RAM upgrade that gave 64k base RAM + 128k XRAM (i.e. 128k was added with a pcb to the existing base RAM) for a total of 192k RAM. There was also a DOS 2.5 ramdisk driver for it (giving 1010 free sectors, showing 999+ free sectors when empty, just like Medium/Enhanced Density). Maybe this is the upgrade you have found ? If so, Simcheck 1.5 shows the correct result... Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 27, 2023 Share Posted January 27, 2023 On 1/24/2023 at 5:32 PM, af0l said: Is there any chance you can provide some better pictures of the bottom? Quote Link to comment Share on other sites More sharing options...
+af0l Posted January 27, 2023 Author Share Posted January 27, 2023 Just now, reifsnyderb said: Is there any chance you can provide some better pictures of the bottom? This is what I have. I have put the machine together for now. I'll play with it during the weekend and repot what I find. Quote Link to comment Share on other sites More sharing options...
+af0l Posted January 27, 2023 Author Share Posted January 27, 2023 39 minutes ago, CharlieChaplin said: Think I read somewhere about an SAG RAM upgrade that gave 64k base RAM + 128k XRAM (i.e. 128k was added with a pcb to the existing base RAM) for a total of 192k RAM. There was also a DOS 2.5 ramdisk driver for it (giving 1010 free sectors, showing 999+ free sectors when empty, just like Medium/Enhanced Density). Maybe this is the upgrade you have found ? If so, Simcheck 1.5 shows the correct result... Possible, but why stick 256mb inside then, and not use it? Seems like a waste. Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 27, 2023 Share Posted January 27, 2023 That might work. Thanks! Quote Link to comment Share on other sites More sharing options...
+af0l Posted January 27, 2023 Author Share Posted January 27, 2023 But I got the machine from Holland + it just feels like a nice quality homebrew. I wish I knew more Dutch than a cuss word and "Oude computer in doos" Quote Link to comment Share on other sites More sharing options...
+tf_hh Posted January 27, 2023 Share Posted January 27, 2023 13 hours ago, CharlieChaplin said: Afaik, the german Atari Magazin RAM upgrade does NOT replace 64k RAM with 256k RAM, instead it adds 256k RAM to the base 64k RAM giving a total of 320k RAM. The german Atari Magazin upgrade was/is Rambo, TOMS, Newell, Peterson, ... compatible using blocks 8ACE and NOT Compyshop compatible (which uses blocks 26AE). Or am I completely wrong ?!? http://www.b-pahl.de/atari8bit/RAM-Disk/ram-disk.html Surely after 40 years I´m not pretty sure, but it was a german magazine. But this kind of expansions I´ve experienced in a very different ways with different 74s chips used in different computers. The scheme behind was always the same: Using 8 pieces 41256 chips (total 256 KB) and divide them in 64 KB main memory and 192 KB banked memory. 13 hours ago, CharlieChaplin said: Attached a scan of the german Atari Magazin article, that even has "320KByte" in the title... (320KByte do-it-yourself) and somewhere in the text it says Rambo compatible... This not the correct one. I´m tried to find the article, but failed so far. 1 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 27, 2023 Share Posted January 27, 2023 (edited) I think that moving the joystick to the right will set whether this expansion provides 128k or 192k. It appears to set whether or not PB6 is considered when setting the banks. My guess is there may be a db9 connector with a toggle switch involved. Looking closely at the board, it's as though it was laid out by hand then etched in a tank. It's an interesting piece. Edited January 27, 2023 by reifsnyderb Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 27, 2023 Share Posted January 27, 2023 Most likely schematic. Needs verified. 1 Quote Link to comment Share on other sites More sharing options...
ClausB Posted January 27, 2023 Share Posted January 27, 2023 There looks to be a white wire from the resistor to RAM pin 1, not called out in your schematic. That would be MA8. 1 Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted January 27, 2023 Share Posted January 27, 2023 15 minutes ago, ClausB said: There looks to be a white wire from the resistor to RAM pin 1, not called out in your schematic. That would be MA8. Thanks! I may find a couple more things once I lay out the board. I saw I also missed the capacitor. (It's probably 100nF.) Quote Link to comment Share on other sites More sharing options...
+af0l Posted January 27, 2023 Author Share Posted January 27, 2023 24 minutes ago, reifsnyderb said: Thanks! I may find a couple more things once I lay out the board. I saw I also missed the capacitor. (It's probably 100nF.) Wow! You're quick! Quote Link to comment Share on other sites More sharing options...
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