1541 won't work on VIC20

[ka2qep]

Good evening, maybe you can help me. I have a Vic20 that is used on a assembly machine. The 1541 disk drive is ok, i tried another 1541 too. My Vic is not sending the right signal out to the 1541 drive. This setup was working since 1984. The only thing I get on the monitor is searching for *. My normal entry is: LOAD"*",8 the hit the RETURN KEY. I do not hear or see any change from the drive. I have a spare with video issues. Is there a driver chip i can swap maybe? Thank you, William DiCarlo KA2QEP New Jersey.

 

[robert_sissco]

Do the floppy drives work on other VIC-20's or C64's? If so, and if your VIA chis are socketed, try switching then. I suspect you will lose the blinking cursor and have no response from the keyboard.

If so, you need to replace the bad VIA.

 

[bear]

I thought there was some timing incompatibility between the VIC-20 and 1541, and this is why there is a VIC-1540? I probably don't understand correctly; I've always been fuzzy on this point.

 

[Timo W.]

I think it as the other way around: the 1541 was made because the C64 could not use the 1540. The VIC-20 can use either.

 

[cwathen]

Had the same problem with my VIC 20 a few years ago. Swapping the 6522 VIAs around and seeing if that kills the keyboard is a good place to start, but in my case it was actually the buffers (7406 chip). They're still readily available brand new very cheaply. Also if it is the 7406 you can piggy back a new chip onto the original chip to see if that fixes the problem before committing to desoldering the old chip. Worth a try if swapping 6522s doesn't seem to do anything.

 

[robert_sissco]

I think it as the other way around: the 1541 was made because the C64 could not use the 1540. The VIC-20 can use either.

You are correct, the 1540 was to FAST for the C64, the 1541 had a ROM that slowed it down. Part of the reason that true 1540's are so rare is that people upgraded them to 1541 with the updated ROM chips to avoud purchasing a new drive when they upgraded their computers.