Do you change the speed of the 1541?

[ral-clan]

Hi,

I never load that little program that speeds up the 1541 to VIC-20 speeds. I never seem to have a problem, either.
Do you guys do this, or not?

[srowe]

You mean the "UI-" command? It's not mandatory to use it but it removes a 40uS delay that is needed with the C64. Using it should mean that data transfers are faster, but I've never measured it.

[eslapion]

You mean the "UI-" command? It's not mandatory to use it but it removes a 40uS delay that is needed with the C64. Using it should mean that data transfers are faster, but I've never measured it.

I have a VIC-1541 which is fitted with a switchable ROM so I checked the difference in loading time of a 16k file on a VIC-20 (NTSC) between the VIC-1540 firmware and the normal 1541 firmware. There is less than 10% difference, really.

I suspect the C64 wouldn't even need this delay if the screen is blanked during disk access as with datasette access. The Super Snapshot V4 and V5 do it to get better CPU performances with their very fast disk accelerator.

[Boray]

The difference is 21% faster (when I measured my PAL machines).

[eslapion]

The difference is 21% faster (when I measured my PAL machines).

That would make sense since the PAL VIC-20 is 10% faster than the NTSC one.

1.1x1.1=1.21