joeventura Posted July 5, 2009 Share Posted July 5, 2009 I have two Bit3 video cards, one works perfectly, the other has an issue which you will see in the photos I am attaching. It appears like a bit is set high or something because there is a solid vertical line at each character. I have tried reseating all the chips and cleaning up the edge connector so far no dice. Any ideas. Quote Link to comment Share on other sites More sharing options...
Rybags Posted July 6, 2009 Share Posted July 6, 2009 Got some pics of the card? A bit of a shot in the dark - maybe the problem is related to the data input to the video controller itself and not the RAM. Quote Link to comment Share on other sites More sharing options...
candle Posted July 6, 2009 Share Posted July 6, 2009 seems like D1 (or D6 depending on memory organisation) is open and has constant "1" on it check character rom chip Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 6, 2009 Author Share Posted July 6, 2009 I will check. Just to clarify the pics you are looking at are from two different BIT3 cards, one that does not have the problem and one that does. I will swap the Char ROM chips first and see if that helps. The data being input is on the same atari 800 from BASIC cart so its not what is being sent to the card or the computer as they are consistent unless you are implying that the two cards interact with the same Atari 800 differently? Quote Link to comment Share on other sites More sharing options...
candle Posted July 6, 2009 Share Posted July 6, 2009 nope i belive this cart has its own memory like xep80 do - this is pure function of 6845 or similiar controller not accesing its fonts definitions properly - i don't think rom may gone bad, it could just oxidise try cleaning the socket with some isoprophyl acohol, or better - with kontakt 60 (www.crcind.com) you may also clean pins of the ic with plain paper (use the chip as "pencil") Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 7, 2009 Author Share Posted July 7, 2009 Well through process of elimination (swapping one chip at a time with a working BIT3) It turns out it is a bad chip. The chip is a 28 pin DIP Labeled: CRT 8021 SMC8313 Quote Link to comment Share on other sites More sharing options...
Rybags Posted July 7, 2009 Share Posted July 7, 2009 Maybe get someone to burn you another EPROM. /wonders... can this thing be simply copied by just plugging into an empty cartridge... Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 7, 2009 Author Share Posted July 7, 2009 its not a rom/eprom sadly its a Non-VGA Video Controller I am searching out one online now, so far I know I can get one if I order $300 worth Lets see what responses I get. I am attaching the datasheet for the chip in case anyone needs help sleeping CRT8021_1654346.pdf Quote Link to comment Share on other sites More sharing options...
Rybags Posted July 7, 2009 Share Posted July 7, 2009 Ah... I thought it was just the charROM. Since it's an off-the-shelf type thing, one strategy might be to see if you can find other devices that used it. Pick said device up from junk pile, and grab CRT Controller from within. Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 7, 2009 Author Share Posted July 7, 2009 Yes I will try that route as well, see what comes up Quote Link to comment Share on other sites More sharing options...
candle Posted July 7, 2009 Share Posted July 7, 2009 Joe! WRONG IC! this is the controller, not character ROM it doesn't have data bus, just address buss to address character rom, and few simple control lines to controll all its operation (stroke, blink, underline, reverse video, three graphics modes) could You post some high-quality pictures of internals of the cart? i could point You the one to suspect then Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 7, 2009 Author Share Posted July 7, 2009 Candle are you reading the thread? I never said it was the Char Rom, I said it was the controller. (CRT8021) The problem has been identified as this chip which I know is a controller not a ROM/Eprom The reason I know is I took a CRT8021 off of a working BIT3 card and swapped it with the one on the problem card and it works fine. Quote Link to comment Share on other sites More sharing options...
Rybags Posted July 7, 2009 Share Posted July 7, 2009 I'm thinking here, old terminals maybe. Probably not IBM 3270 types. Maybe VT52, 100s? Or something from HP, Wang, Prime or Unisys. Problem is, a lot of that stuff just got scrapped around the late 1980s when PC-based terminal emulation became popular. It might be the case that such terminals themselves, although practically useless, are regarded as collectors items. Quote Link to comment Share on other sites More sharing options...
sl0re Posted July 7, 2009 Share Posted July 7, 2009 I'm thinking here, old terminals maybe. Probably not IBM 3270 types. Maybe VT52, 100s? Or something from HP, Wang, Prime or Unisys. Problem is, a lot of that stuff just got scrapped around the late 1980s when PC-based terminal emulation became popular. It might be the case that such terminals themselves, although practically useless, are regarded as collectors items. If you google the chip then some of the equipment that used it will probably come up in the search. Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 7, 2009 Author Share Posted July 7, 2009 Hmmm good idea, possibly a Wyse terminal (which I have sitting on the shelf) Quote Link to comment Share on other sites More sharing options...
candle Posted July 7, 2009 Share Posted July 7, 2009 Joe, despite Your belive in bad controller - could You analyse its case a little futher? especially the way character rom is addressed and video signal formed Quote Link to comment Share on other sites More sharing options...
peteym5 Posted July 7, 2009 Share Posted July 7, 2009 I never heard of these boards, probably because they were not sold in the U.S. (AFAIK) What are the capabilities and how are they attached? Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 7, 2009 Author Share Posted July 7, 2009 Joe, despite Your belive in bad controller - could You analyse its case a little futher?especially the way character rom is addressed and video signal formed Can you give me something further to try? I am at a loss I swapped the Char roms the problem persisted I swapped out the controller the problem went away I don't have a scope nor schematics so aside from swapping chips what do you suggest? Quote Link to comment Share on other sites More sharing options...
Rybags Posted July 7, 2009 Share Posted July 7, 2009 Maybe something simple like do continuity tests with a multimeter from the Dn lines on the ROM to their destinations on the controller or wherever they go to. Quote Link to comment Share on other sites More sharing options...
Mathy Posted July 7, 2009 Share Posted July 7, 2009 (edited) Hello peteym5 It's a "right cartridge". With a convertor PCB it might work in an XL or XE too. It was made (or at least developed and sold) by an American company. It displays up to 80 characters per line. greetings Mathy Edited July 7, 2009 by Mathy Quote Link to comment Share on other sites More sharing options...
sl0re Posted July 8, 2009 Share Posted July 8, 2009 Hello peteym5 It's a "right cartridge". With a convertor PCB it might work in an XL or XE too. It was made (or at least developed and sold) by an American company. It displays up to 80 characters per line. greetings Mathy I have one, it's in memory card form (800). Neat product though. If someone wanted to redo it as a PBI or in the case hack it would be cool. Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 8, 2009 Author Share Posted July 8, 2009 Hello peteym5 It's a "right cartridge". With a convertor PCB it might work in an XL or XE too. It was made (or at least developed and sold) by an American company. It displays up to 80 characters per line. greetings Mathy no its a card that goes in the last slot of an 800. Replaces the last memory card. Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 8, 2009 Author Share Posted July 8, 2009 Maybe something simple like do continuity tests with a multimeter from the Dn lines on the ROM to their destinations on the controller or wherever they go to. Don't understand the logic of that test, remember that putting another chip in its place corrects the problem. Quote Link to comment Share on other sites More sharing options...
Rybags Posted July 8, 2009 Share Posted July 8, 2009 Sorry, I'd just woken up and forgotten your previous diag report... looks like the "needs new controller IC" is the answer. Quote Link to comment Share on other sites More sharing options...
joeventura Posted July 8, 2009 Author Share Posted July 8, 2009 If anyone has a contact or source for an SMC CRT8021 Video controller chip (28 pin DIP) Please let me know. Obsolete chip dealers wont talk to me unless I want to buy 100 or more of them. Or if you know for certain any piece of hardware that may utilize one on their board. Quote Link to comment Share on other sites More sharing options...
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