A500 External fdd problems ...

[ognix]

Hello!

Very strange problem...
I would say weak supply current as well, if problems would occur also on Mortal Kombat and X-Copy.

I'm not deep into AmigaDOS and inner working details, but since Mortal Kombat and X-Copy are not using (I assume) DOS routines to access drives, the problem is realated to DOS disk routines (trackdisk.device?).
Maybe DOS routines are making a kind of "deeper and verified" reading, to make sure of the data (unless maybe NDOS/proprietary routines).

If so, I think that going with OS 3.1 wouldn't change anything.


Since the long chain it could be a slight impedance mismatch on the lines that provides error just on the more "severe" DOS routines.
I should check schematics to understand well...
But it's just a guess...

Anyway try another thing (if not already done): try connecting the 3 external drives in a different order (eg. switch DF1 with DF3).
This to check if there is a problem in the pass-through connector behind the drive (eg. a bad contact on DF1 one may create problems on DF2 and DF3 - this would explain why they are working well alone).

BY!

[ognix]

Thanks...

Anyway three drives are quite a lot for the original power supply, especially if you have the oldest one (the heavier ones); newer ones were supplied with A500+ and delivered 4,5A on 5V line (if not wrong).
The older ones 3A or less current.

Maybe a mix of reasons... (weak current lead to reduced voltage levels -> less noise immunity, etc.).

Thanks for greetings: I've been in Split this August for a week with 4 friends of mine (Strobec camping to be precise).  ;-)