hans@nlgvax.UUCP (Hans Zuidam) (08/10/88)
This is for a collegue of mine... ------------------------------------------------------------------------ From: Andrew Dickman (Philips Telecommunications and Data Systems) Subject: Amiga 500 external floppy disk failure We have an Amiga 500 which (after booting) thinks it has 4 disk drives: 1 internal and 3 external. The three external ones are marked "BAD". What happens during power-up is the following (according to the manuals): 1. Each possible external drive is selected and it's motor-on line is pulsed. 2. This then informs the drive to send it's identification. 3. The Amiga reads this bitstream back and depending on the returned value it determines the drive type: $FFFFFFFF 3.5" $55555555 5.25" $00000000 no disk Now when the software boots, it goes through all detected disks and tries to find out what they are (KICK, DOS). Because the drives are not there they are marked bad. Booting takes ages this way. We suspect that's it has something to do with pin 1 on CN5 (_RDY) (Does the "_" means active low?). This line remains low during startup. Adding a 4K7 pull-up resistor 4K7 doesn't. If anyone has a hint on where to look or what to do, we are greatfull. Andrew -- Hans Zuidam E-Mail: hans@nlgvax.UUCP Philips Telecommunications and Data Systems, Tel: +31 40 892288 Project Centre Geldrop, Building XR Willem Alexanderlaan 7B, 5664 AN Geldrop The Netherlands
grr@cbmvax.UUCP (George Robbins) (08/15/88)
In article <238@nlgvax.UUCP> hans@nlgvax.UUCP (Hans Zuidam) writes: > From: Andrew Dickman (Philips Telecommunications and Data Systems) > Subject: Amiga 500 external floppy disk failure > > We have an Amiga 500 which (after booting) thinks it has 4 disk drives: > 1 internal and 3 external. The three external ones are marked "BAD". > > We suspect that's it has something to do with pin 1 on CN5 (_RDY) (Does > the "_" means active low?). This line remains low during startup. Yep, this is a low active signal. I've seen this problem before. It usually idicates that either some drive is holding ready low all the time or there is a short on the board that is grounding ready. Other possibilities are that the 8520 that ready goes into is blown or one of the select lines is always being held low. The gary chip handles this for the internal drive, so conceivably it could be blown also... -- George Robbins - now working for, uucp: {uunet|ihnp4|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@uunet.uu.net Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)