15

I have both a beige VIC-20 styled VIC-1541 disk drive and the later brown C64 1541 drive. Is there a difference between them (besides how they look)?

  • 2
    Per this, they had different defects that prevented them from using the serial bus at full speed. – Mark Apr 27 '16 at 20:47
  • 5
    Just for clarity the drives didn't have different defects, the VIC and C64 did. The VIC-1540 and VIC-1541 disk drives are different drives. The OP is asking only about the VIC-1541 and the regular 1541. – Payton Byrd Apr 28 '16 at 1:52
15

Functionally there is no difference between the VIC-1541 and 1541. Internally, there may be lots of differences due to production variation and component variation. The thing to remember is that both drives have modes to directly support the VIC-20 and C64. The VIC-20 is actually faster reading data when the drive is in 1540 mode instead of 1541 mode, but ANY 1541 drive supports 1540 mode.

  • 1
    Can a C64 be made to load data using the 1540 mode? – cbmeeks May 15 '17 at 14:21
  • 2
    @cbmeeks a C64 can tell a 1541 to use 1540 mode, but you have to blank the screen while using it. The issue is that the VIC-20 always had the CPU running to listen to the data coming from the disk over the serial bus, but the VIC-II chip in the C64 stole about 40 CPU cycles for every scanline thus making it that the C64 would miss a little data here and there because it wasn't listening. If you temporarily disable the VIC-II it will no longer steal CPU cycles and thus 1540 mode will work. I'm guessing some loaders used this, but we're talking a VERY SMALL speed improvement in reality. – bjb May 8 '18 at 17:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.