Eudimorphodon
Veteran Member
Trying to be optimistic about my prospects for getting a PET working someday...
I've been looking at the disk drives I picked up from the Albany Computer Services warehouse dump. I have two of the big dual-chassis drives, an 8050 and a 2040 that has a sticker on it that says "Updated to 2.0" (And then the 2.0 is scratched out and "2.1" is written underneath it.) The 8050 appears to pass diagnostics. (I won't know any more than that until I can get a working machine to drive it with.) The 2040, however, goes into a loop where it blinks all its LEDs three times, pauses, repeats.
According to the Commodore 8050 service manual (I can't seem to find a 2040/4040 specific flash decoder) three blinks means a bad DOS ROM. So, two questions:
1: Since I can't seem to find the 2040 blink codes, does anyone know which ROM three blinks translates to? (The 8050 appears to use 8k ROMs while the 2040 is 4k.) I'd love to not have to burn replacements for all three because of question #2.
2: Is there an EPROM that's a close-to-drop-in replacement for the ROMs in the 2040? I did find this thread:
http://www.vintage-computer.com/vcf...pairing-a-Commodore-2040-IEEE-488-drive/page3
And if I'm interpreting it at all correctly unlike a PET's 4k ROMs I can't simply drop in a 2532 because pin 21 is a TTL chip select line instead of being tied to 5+ volts? There's also mention of a speed-related issue. (I believe the 2532s I have access to are 450ns.) My *guess* is that my best bet is to make adapters for 2732s like these:
http://personalpages.tds.net/~rcarlsen/tdsweb/EPROM/2732sub.gif
But I'm wondering if anyone has better ideas. (Of course, with my luck it's not going to be a bad ROM at all...)
Thanks.
I've been looking at the disk drives I picked up from the Albany Computer Services warehouse dump. I have two of the big dual-chassis drives, an 8050 and a 2040 that has a sticker on it that says "Updated to 2.0" (And then the 2.0 is scratched out and "2.1" is written underneath it.) The 8050 appears to pass diagnostics. (I won't know any more than that until I can get a working machine to drive it with.) The 2040, however, goes into a loop where it blinks all its LEDs three times, pauses, repeats.
According to the Commodore 8050 service manual (I can't seem to find a 2040/4040 specific flash decoder) three blinks means a bad DOS ROM. So, two questions:
1: Since I can't seem to find the 2040 blink codes, does anyone know which ROM three blinks translates to? (The 8050 appears to use 8k ROMs while the 2040 is 4k.) I'd love to not have to burn replacements for all three because of question #2.
2: Is there an EPROM that's a close-to-drop-in replacement for the ROMs in the 2040? I did find this thread:
http://www.vintage-computer.com/vcf...pairing-a-Commodore-2040-IEEE-488-drive/page3
And if I'm interpreting it at all correctly unlike a PET's 4k ROMs I can't simply drop in a 2532 because pin 21 is a TTL chip select line instead of being tied to 5+ volts? There's also mention of a speed-related issue. (I believe the 2532s I have access to are 450ns.) My *guess* is that my best bet is to make adapters for 2732s like these:
http://personalpages.tds.net/~rcarlsen/tdsweb/EPROM/2732sub.gif
But I'm wondering if anyone has better ideas. (Of course, with my luck it's not going to be a bad ROM at all...)
Thanks.