Just Jeff Posted May 27, 2019 Share Posted May 27, 2019 Good Morning, I bought a Commodore 64 on Ebay and it seems to work fine, but the startup screen says 11122 Basic Bytes Free. Isn't it supposed to show 38000 more or less? Does anyone have any idea what is causing that? Bad RAM? Quote Link to comment Share on other sites More sharing options...
carlsson Posted May 27, 2019 Share Posted May 27, 2019 Yes, it should say 38911. Probably you have faulty RAM and the startup routine stops counting. 11122 bytes counting from address 2048 would equal 13170 ($3372). If it boots to BASIC, I suppose you could POKE and PEEK around there to see if you get back the values you store. Exactly what it means of actual RAM chips would need to be looked up. 1 Quote Link to comment Share on other sites More sharing options...
thetick1 Posted May 29, 2019 Share Posted May 29, 2019 (edited) Are you sure it is C64 ? Can you show a screenshot of bytes free and if possible a picture of the case and motherboard ? If it is a C64 then see https://retrocomputerverzamelaar.nl/commodore-64-problems/ RAM Problems U9 – U12, U21 – U24 DescriptionStartup screen problems with: out of memory error, wrong number of memory available, colored random characters. GeneralBlank screen, no border. Shorted chips may get warmer (sometimes very hot) than the other RAM chips. Partial failure: will sometimes produce “garbage” screen, abnormal number of bytes free (lower than 38911) or “OUT OF MEMORY IN 0” error on startup screen. Cause Bad RAM chips or bad socket contacts of the RAM(M41464) 2 RAM CHIPS (64K X 4 DRAM) Please see description of the images for the cause Edited May 29, 2019 by thetick1 1 Quote Link to comment Share on other sites More sharing options...
carlsson Posted May 29, 2019 Share Posted May 29, 2019 What else would it be? A VIC-20 with 8K expansion should report 11775 bytes free, and the expansion normally is external anyway. 1 Quote Link to comment Share on other sites More sharing options...
Just Jeff Posted May 29, 2019 Author Share Posted May 29, 2019 Thanks yes its a c64. Says so on the top, and the screen. In fact the screen says its 64K at the top. Carlsson- do you have a website? I was looking around for more info today and found one repair site run by someone with that name. Quote Link to comment Share on other sites More sharing options...
carlsson Posted May 29, 2019 Share Posted May 29, 2019 Yes, I've got a website but the site you found most likely is Ray Carlsen's site, which obviously is not me. http://personalpages.tds.net/~rcarlsen/cbm/ Quote Link to comment Share on other sites More sharing options...
Just Jeff Posted May 29, 2019 Author Share Posted May 29, 2019 Ah.. OK I tried pokes and peeks. I don't seem to be able to use the $ though. I can peek (3371), (3372), and (3373) and get 0,255,0 respectively. When I poke 9 to those 3 locations, I peek a 9 back. I'm not that familiar with BASIC anymore... In my world, leaving the $ off means I am using a decimal number instead of a hexadecimal. Is that the difference here? Quote Link to comment Share on other sites More sharing options...
carlsson Posted May 30, 2019 Share Posted May 30, 2019 Ah, my mistake. You should POKE 13170 and subsequent addresses. The hexadecimal notation I gave was just for reference as I believe I've seen you in the Atari 2600 programming forum where you'd know hexadecimal by heart. Quote Link to comment Share on other sites More sharing options...
Just Jeff Posted May 31, 2019 Author Share Posted May 31, 2019 Ahh then you've probably seen my quixotic attempts to make an Atari 2600 become a Commodore 64 So yeah its acting funny: poke 255 in peek 13170 055 13171 239 13172 didn't write it down but I think it was 255 13173 132 poke 0 13170 055 13171 039 What do you think? Quote Link to comment Share on other sites More sharing options...
carlsson Posted June 1, 2019 Share Posted June 1, 2019 I believe you have a partly damaged RAM chip, unless there is something else that can cause part of the memory to work but part doesn't. The PLA chip is a kind of memory manager I think but it probably would be greater errors if it was the cause. Quote Link to comment Share on other sites More sharing options...
Just Jeff Posted June 3, 2019 Author Share Posted June 3, 2019 So from what I've read. I should buy a few chips, then piggyback one at a time to see if results change? Quote Link to comment Share on other sites More sharing options...
ToddL Posted June 14, 2019 Share Posted June 14, 2019 Yes, I've got a website but the site you found most likely is Ray Carlsen's site, which obviously is not me. http://personalpages.tds.net/~rcarlsen/cbm/ He has a new website although the repair information seems to still link to the old website at least for now: http://carlsenelectronics.net/ 1 Quote Link to comment Share on other sites More sharing options...
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