DavidMil Posted December 5, 2016 Share Posted December 5, 2016 Does anyone remember which manufacturer of 16K RAM chips for the old 800's had a very high failure rate? Thanks, DavidMil Quote Link to comment Share on other sites More sharing options...
Rybags Posted December 5, 2016 Share Posted December 5, 2016 Was there one? XE especially and XL to a lesser degree have the notorious MT chips which some people will just replace even if not (yet) gone bad. There were actually "not passed" Ram chips used in some Ram cards - I think maybe only the 8K. What happened was 4416 chips didn't have a great yield rate as was the norm in the day but some were good enough that they had 50% of contiguous good rows so could be sold (as 4408 ?) - there was an article (Creative Computing I think) which showed how to turn an 8K into a 16K board by replacing the Ram and making a couple of other mods. 1 Quote Link to comment Share on other sites More sharing options...
DavidMil Posted December 5, 2016 Author Share Posted December 5, 2016 That's right. It was the MT chips. I went back and looked at the 800 and sure enough it has MT chips in it. Two of the three 16K RAM boards are failing SALT RAM test. So I'm going to replace all of them too. Thanks for refreshing my memory Rybags, David Milsop Quote Link to comment Share on other sites More sharing options...
a8isa1 Posted December 6, 2016 Share Posted December 6, 2016 Only memory issue that I can recall for 800s was overheating. Some magazine (maybe Analog Computing) recommended using the memory boards without their cases. My 800 never locked up again. Well, never locked up just sitting idle in BASIC. Quote Link to comment Share on other sites More sharing options...
DavidMil Posted December 6, 2016 Author Share Posted December 6, 2016 Mine used to over heat too. Besides removing the cases from the RAM and ROM boards, I also removed the cover and stuck a tooth pic in the door switch. For awhile I even put a small fan over the PC to help remove heat. DavidMil Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 6, 2016 Share Posted December 6, 2016 All but the earliest 800s came standard with 16K bit DRAM chips, generically called 4116s. My first 800 came with one 16K board and I soon upgraded it to 64K by replacing the 4116s with 4164s as described in the link below. Then I did the same to an Axlon 32K board to get 128K. So I had three banks of 4164s plus many LSTTL chips and never had overheating trouble. http://atariage.com/forums/topic/122750-64k-atari-800/?do=findComment&comment=1482933 Quote Link to comment Share on other sites More sharing options...
Rybags Posted December 7, 2016 Share Posted December 7, 2016 Didn't the 4164 just run on straight +5V ? Given the earlier chips use the +12V supply that'd go a way to explaining the heat issue. 1 Quote Link to comment Share on other sites More sharing options...
ClausB Posted December 7, 2016 Share Posted December 7, 2016 Yes. A 4116 draws 24 mA of 12 V at 1.8 MHz, so 48K worth, or 24 chips, draw 6.8 Watts. A 4164 draws 25 mA of 5 V, so 64K, 8 chips, draw 1.0 Watts. 3 Quote Link to comment Share on other sites More sharing options...
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