Cambouis de l'Atari Posted April 29, 2016 Share Posted April 29, 2016 Hello ! I'm here again with another 800 related question I found this card in my non functional ntsc 800 : Clearly a home made ! There is a switch and a long upper connector, so I guess it's for some kind of interface. Do the IC on the picture give someone a clue about its purposes ? It's just for my information as this 800 seems really in bad shape, so this card is probably dead too (all the rom and ram are ko, and some part of the computer too as I checked it with known working rom and rams). 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted April 29, 2016 Share Posted April 29, 2016 HM6116 are 2K SRam chips. AM2966 is an octal dynamic memory driver IC. What the card is for, no idea. Weird that a memory slot would have something with only 4K occupying it. Maybe it's some sort of printer buffer. Or maybe some sort of interface that allows high speed data transfer to another computer using the 4K as a buffer. 1 Quote Link to comment Share on other sites More sharing options...
ClausB Posted April 29, 2016 Share Posted April 29, 2016 Looks like a homebrew 4KB SRAM board. Are the other two RAM boards 16KB and 32KB? If so, then maybe this one makes 52K total. 2 Quote Link to comment Share on other sites More sharing options...
Cambouis de l'Atari Posted April 29, 2016 Author Share Posted April 29, 2016 Yes, the other ram boards are 16K and 32K (ramcram). Does the Sram mean Static = non volatile ram ? Quote Link to comment Share on other sites More sharing options...
Joey Z Posted April 29, 2016 Share Posted April 29, 2016 (edited) Does the Sram mean Static = non volatile ram ? No. Non-volatile means it doesn't lose contents when the power is removed. Static means that in normal powered on operation, the RAM is stable. This is contrary to Dynamic RAM where each cell is a capacitor, and capacitors (by nature) are leaky, so the DRAM has to be refreshed periodically in order to maintain it's state. EDIT: although I should add that a simple battery and diode circuit is usually enough to keep an SRAMs contents when the power is off, but it'd be useless without software to use it for something, and it'd only be 4K. Edited April 29, 2016 by Joey Z 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted April 29, 2016 Share Posted April 29, 2016 Looks like a homebrew 4KB SRAM board. Are the other two RAM boards 16KB and 32KB? If so, then maybe this one makes 52K total. I didn't think of that... but for 52K isn't modification to the motherboard required? I thought only the select lines for 6 lots of 8K were provided to the memory slots. Quote Link to comment Share on other sites More sharing options...
Joey Z Posted April 29, 2016 Share Posted April 29, 2016 I didn't think of that... but for 52K isn't modification to the motherboard required? I thought only the select lines for 6 lots of 8K were provided to the memory slots. well, maybe there are modifications on the motherboard, Cambouis de l'Atari would have to take a look at the bottom of the motherboard probably, maybe there are extra wires run to slots. Quote Link to comment Share on other sites More sharing options...
ClausB Posted April 29, 2016 Share Posted April 29, 2016 And there is that mysterious connector at the top. Dual-port RAM maybe? Could you photograph the back side of the board? Quote Link to comment Share on other sites More sharing options...
Cambouis de l'Atari Posted April 29, 2016 Author Share Posted April 29, 2016 Sure, but I'm afraid it won't be of much help 3 Quote Link to comment Share on other sites More sharing options...
+MrFish Posted April 29, 2016 Share Posted April 29, 2016 Sure, but I'm afraid it won't be of much help Whoa!... Spaghetti anyone? 1 Quote Link to comment Share on other sites More sharing options...
ClausB Posted May 1, 2016 Share Posted May 1, 2016 Yes, but we can tell something by which card edge pins are wired at the bottom. The only select lines wired are M and P. If this board is meant for slot 3 then those are Y6 and EXSEL. EXSEL is required to address the C000-CFFF region, but so is A13, which is not wired. And Y6 addresses D600-D6FF which doesn't seem useful here. So I am doubting the board is for getting 52K total RAM. If the board is meant for slot 2 then M and P select the 8000-BFFF range, which is upper RAM or cart ROM space. So it could be a dual port ROM simulator for cart development. The connector could take a ribbon cable which runs to a development system, maybe an Apple or another Atari. Which slot was it plugged in to when you got it? Is there a cutout in the lid for a ribbon cable? Quote Link to comment Share on other sites More sharing options...
Cambouis de l'Atari Posted May 1, 2016 Author Share Posted May 1, 2016 This board was in the fartest slot : ROM - 16K - 32K - that board. There is no cutout in the lid. And the lid switch is working, you can't use the 800 with the lid opened. Did you notice the switch on the board ? Can you figure out what it operates ? Could maybe give a clue... Thank you for searching Quote Link to comment Share on other sites More sharing options...
ClausB Posted May 3, 2016 Share Posted May 3, 2016 Hmmm. I tried to trace the yellow wires from the switch but got lost. Quote Link to comment Share on other sites More sharing options...
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