jonweiss Posted March 16, 2011 Share Posted March 16, 2011 I found this board in a Atari 800 I had in the attic. It was in the last slot of the computer. Does anyone know what this is? I couldn't find any information on the web about it. I think it might be a clock card. I have no software for it. Quote Link to comment Share on other sites More sharing options...
fibrewire Posted March 16, 2011 Share Posted March 16, 2011 The part number for the big chip is MC6821P - a peripheral interface adapter for connecting M6800 CPU to peripheral devices. MSM5832RS - RTC... As if the oscillator and battery weren't a dead giveaway Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 16, 2011 Share Posted March 16, 2011 I'd say yes, not much other reason to have a battery other than keeping SRAM alive. I found a datasheet match for a RTC58321 IC which is an RTC chip. There's other variants also like 58323. The 6821 is a PIA. The RTC uses a 4-bit data bus and a few control lines which need to have latched values to function normally. Quote Link to comment Share on other sites More sharing options...
fibrewire Posted March 16, 2011 Share Posted March 16, 2011 I was gonna say that! Quote Link to comment Share on other sites More sharing options...
fibrewire Posted March 16, 2011 Share Posted March 16, 2011 pins 14, 15, 16 for PB4, PB5, PB6 MC6821P.pdf Quote Link to comment Share on other sites More sharing options...
ovalbugmann Posted March 16, 2011 Share Posted March 16, 2011 Anyone know what is this board? IDK, I though this was the atariage.com message-board, but in looking around the site it all looks totally different now. Hmmm. Quote Link to comment Share on other sites More sharing options...
fibrewire Posted March 16, 2011 Share Posted March 16, 2011 Answers for 'New Forum Look' are covered here Quote Link to comment Share on other sites More sharing options...
guus.assmann Posted March 16, 2011 Share Posted March 16, 2011 Hello, It is a RTC. And the parts used are the same as in a design I've made long ago. I've attached the schematic diagram and the driver software for the design that I've made. The datasheet for the clock chip should also be available. (And I will have it somewhere as well) All data should enable you to use the parts. BR/ Guus Dos25_Clock.atr Quote Link to comment Share on other sites More sharing options...
jonweiss Posted March 16, 2011 Author Share Posted March 16, 2011 Hello, It is a RTC. And the parts used are the same as in a design I've made long ago. I've attached the schematic diagram and the driver software for the design that I've made. The datasheet for the clock chip should also be available. (And I will have it somewhere as well) All data should enable you to use the parts. BR/ Guus Thanks guys, I thought thats what it was. It's taking one of the slots so it doesn't have the full 48K of memory. Quote Link to comment Share on other sites More sharing options...
sloopy Posted March 16, 2011 Share Posted March 16, 2011 get a 32k mem card for your 800, and then you will have 48k and the clock... sloopy. Quote Link to comment Share on other sites More sharing options...
+Stephen Posted March 16, 2011 Share Posted March 16, 2011 Or you could sell me the RTC I'll even throw in an extra 16kB RAM card if you need it to fill the void. Quote Link to comment Share on other sites More sharing options...
puppetmark Posted March 17, 2011 Share Posted March 17, 2011 The datasheet for the clock chip should also be available. (And I will have it somewhere as well) All data should enable you to use the parts. Here is tthe datasheet for the clock chip: MSM5832.pdf Quote Link to comment Share on other sites More sharing options...
Defender II Posted March 19, 2011 Share Posted March 19, 2011 Let me know if you decide to sell it. Quote Link to comment Share on other sites More sharing options...
fibrewire Posted July 25, 2013 Share Posted July 25, 2013 According to this the PIA 6821 is the same as the 6520A used in the Atari 800, although pin 35 & 36 seem to be switched. Could another PIA be attached to the data bus in a plug in card to add more interfaces without disabling the existing Port A and Port B? Quote Link to comment Share on other sites More sharing options...
guus.assmann Posted July 25, 2013 Share Posted July 25, 2013 (edited) Hello fibrewire, Yes that can be done. And it's not too difficult. But it would need a small change to the addressing of the original PIA. Again. not difficult. But it does involve (intrusive) change of the Atari parts. BR/ Guus Edited July 25, 2013 by guus.assmann Quote Link to comment Share on other sites More sharing options...
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