giobbi
Veteran Member
Hi,
Reading an old post and the web page http://vintagemashups.net/2010/12/commodore-1541-ieee-488-conversion/ about how to convert a 1541 drive and make it suitable for PET, using the IEEE-488 protocol, I decided to do a try. So I bought the needed ICs, I built a pcb and, as usual, I have a little, simple problem... nothing works :smile:: no answer calling the drive from my 8032-sk and no reset when I switch on and off the 8032.
Of course I checked my PCB (and I will check it again and again), but I've noticed the drive has a strange behavior with the patched ROM image I downloaded from the above site.
- with the original ROM, as usual, the floppy starts to spin and the red light comes on; after few seconds, the light and the spin motor go off in the same moment. Normal behavior.
- with the patched ROM, the floppy just spins for a while and then stops, while the red light stays on for a longer time (and then goes off).
Note that the strange behavior doesn't depend from the interface board; I tried to put the patched EPROM and leave the 6522 into its socket, without the ieee interface board, and the behavior is the same. I think it's quite strange: Shouldn't it have the same reset procedure, even with the modified ROM image?
I'm only sure that:
- the 1541 drive is ok
- the 6522 is ok
- the socket adapter is ok
- the EPROM im programmed returns no difference if compared with the patched rom image (so I believe it's ok too)
- the ieee cable an connectors are ok
then, probably, the issue is with my board or with the patched ROM image.
So here there are my two question for you, smart people:
1) Anybody that understand ML, can take a look to the patched ROM from the vintagemashup.net site, compare it with the original ROM 901229-05 and tell me if this different behavior during the drive boot is ok? I know it's a lot of work, but maybe somebody here likes to compare hex files? ;-)
2) looking at schematics and at the project (http://www.zimmers.net/anonftp/pub/cbm/documents/projects/ieee-488/index.html), can you tell me how the jumpers work? i.e. no jumpers = drive 8, all jumpers = drive 11, etc.?
thank you,
Giovi
p.s. OH OH OH I have a scope! Finally, I have a scope! I'm not sure if it would be useful for this problem, but I have it
Reading an old post and the web page http://vintagemashups.net/2010/12/commodore-1541-ieee-488-conversion/ about how to convert a 1541 drive and make it suitable for PET, using the IEEE-488 protocol, I decided to do a try. So I bought the needed ICs, I built a pcb and, as usual, I have a little, simple problem... nothing works :smile:: no answer calling the drive from my 8032-sk and no reset when I switch on and off the 8032.
Of course I checked my PCB (and I will check it again and again), but I've noticed the drive has a strange behavior with the patched ROM image I downloaded from the above site.
- with the original ROM, as usual, the floppy starts to spin and the red light comes on; after few seconds, the light and the spin motor go off in the same moment. Normal behavior.
- with the patched ROM, the floppy just spins for a while and then stops, while the red light stays on for a longer time (and then goes off).
Note that the strange behavior doesn't depend from the interface board; I tried to put the patched EPROM and leave the 6522 into its socket, without the ieee interface board, and the behavior is the same. I think it's quite strange: Shouldn't it have the same reset procedure, even with the modified ROM image?
I'm only sure that:
- the 1541 drive is ok
- the 6522 is ok
- the socket adapter is ok
- the EPROM im programmed returns no difference if compared with the patched rom image (so I believe it's ok too)
- the ieee cable an connectors are ok
then, probably, the issue is with my board or with the patched ROM image.
So here there are my two question for you, smart people:
1) Anybody that understand ML, can take a look to the patched ROM from the vintagemashup.net site, compare it with the original ROM 901229-05 and tell me if this different behavior during the drive boot is ok? I know it's a lot of work, but maybe somebody here likes to compare hex files? ;-)
2) looking at schematics and at the project (http://www.zimmers.net/anonftp/pub/cbm/documents/projects/ieee-488/index.html), can you tell me how the jumpers work? i.e. no jumpers = drive 8, all jumpers = drive 11, etc.?
thank you,
Giovi
p.s. OH OH OH I have a scope! Finally, I have a scope! I'm not sure if it would be useful for this problem, but I have it