+Larry Posted February 17, 2014 Share Posted February 17, 2014 I've had lots of problems with these "used good" 27C512 eproms that are typically found on eBay and even major suppliers. They all seem to erase OK, but more than half seem to have programming issues -- "device did not program." If I program/erase several times, then more than half eventually get programmed correctly. I use these in my Atari's typically in Dropcheck's 4-in-1 OS adapter. Are there better alternatives? EEproms? Some type of regular PLCC flash chip with 27C512-compatible adapter? Thanks, Larry Quote Link to comment Share on other sites More sharing options...
Marius Posted February 17, 2014 Share Posted February 17, 2014 Are you sure you erase long enough? Is the windowglass absolutely clean? Is there a feature that let you program slower? Quote Link to comment Share on other sites More sharing options...
+Larry Posted February 17, 2014 Author Share Posted February 17, 2014 Are you sure you erase long enough? Is the windowglass absolutely clean? Is there a feature that let you program slower? Passes blank checks with no issues. Unfortunately, I can't slow down the programming. Glass is spotless, but that would only affect erasing. But I have stopped throwing them away -- I have a new programmer coming that may have more features -- certainly programs many, many more devices. -Larry Quote Link to comment Share on other sites More sharing options...
Bryan Posted February 17, 2014 Share Posted February 17, 2014 Yeah, I'd suspect the programmer rather than the EPROMs. Quote Link to comment Share on other sites More sharing options...
MrMartian Posted February 17, 2014 Share Posted February 17, 2014 I just want to say, I have lots of experience with EPROMS that blank check after erasing, but fail during programming. I pretty much always erase my devices for 30-35 minutes instead of the typical 20-25 just to ensure this doesn't happen.. Quote Link to comment Share on other sites More sharing options...
Roydea6 Posted February 17, 2014 Share Posted February 17, 2014 The 27c512 pulls that I have used I agree if not Double erase time use I get failed programed notice also.. I agree with the Double erase time needed. Quote Link to comment Share on other sites More sharing options...
re-atari Posted February 19, 2014 Share Posted February 19, 2014 (edited) I've had lots of problems with these "used good" 27C512 eproms that are typically found on eBay and even major suppliers. They all seem to erase OK, but more than half seem to have programming issues -- "device did not program." If I program/erase several times, then more than half eventually get programmed correctly. I use these in my Atari's typically in Dropcheck's 4-in-1 OS adapter. Are there better alternatives? EEproms? Some type of regular PLCC flash chip with 27C512-compatible adapter? In the past I have had nothing but trouble with National Semiconductor eproms (notable nms27c128 and nms27c256) pulled from old VGA cards, when trying to program them on a Willem programmer (first revision). IIRC these required 13,5V programming voltage instead of the 'standard' 12,5V. Only found that out after I switched to a Hi-Lo All-07. But, as you already have a dedicated eprom programmer at hand, you can switch over to using flashroms. From my own experience, a 28F512 or 29F512 will work fine. re-atari Edited February 19, 2014 by re-atari Quote Link to comment Share on other sites More sharing options...
atari8warez Posted February 20, 2014 Share Posted February 20, 2014 (edited) Are there better alternatives? EEproms? Some type of regular PLCC flash chip with 27C512-compatible adapter? Thanks, Larry Larry, you may want to try these, I used these in my OSS 4-in-1 cart mods with success, bought them from eBay, they are used EEPROMS and as such you still have a chance to get bad ones. I purchased a lot of 5 at first and had 2 bad chips in the lot but the vendor sent me another 5 to settle the issue so I can't complain This is the vendor I bought the chips from. The auction page says "New", but I doubt it, none of the EEPROMS where blank. Edited February 20, 2014 by atari8warez Quote Link to comment Share on other sites More sharing options...
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