Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!mit-eddie!bloom-beacon!eru!hagbard!sunic!mcsun!ukc!strath-cs!cs.glasgow.ac.uk!bru-cc!eesrajm From: eesrajm@cc.brunel.ac.uk (Andrew J Michael) Newsgroups: comp.os.minix Subject: Trouble with Amiga floppies - a possible solution Keywords: Amiga floppies MFM Message-ID: <1850@Terra.cc.brunel.ac.uk> Date: 6 Oct 90 08:19:35 GMT Organization: Brunel University, Uxbridge, UK Lines: 43 Having just had a good look at the AmigaMINIX sources, I'm not entirely surprised that there are problems with floppy disks. This is NOT meant as a criticism of AmigaMINIX (quite the opposite, it's VERY clever). It's more a comment on the Amiga's hardware design. From looking at the code, it seems that the Amiga doesn't understand sectors; it only knows about tracks, and raw ones at that. To simulate a normal MFM disk controller, some natty software in the AmigaMINIX kernel manufactures what looks like an MFM track, complete with sector gaps, headers and CRCs and gets the Amiga hardware to write it out to the floppy as a raw track. I don't know exactly how P-H are duplicating the floppies, but I can well see that there might be problems bearing this in mind. So for those who have one of more faulty Amiga MINIX floppies, try the following. It isn't guaranteed to work, but probably worth an attempt. Get someone with a genuine MFM floppy controller to copy the faulty disk(s) for you. The ideal here is an ST; either use something like procopy under TOS, or copy the disks under MINIX if you can read them under ST MINIX. If you can't find an ST, then an IBM with 720k floppies should work. You probably won't be able to copy them with diskcopy, but one of the many disk copying programs supplied for nefarious reasons should cope. The theory here is that the proper MFM controllers like the 1772 in an ST have pretty good error performance, certainly better than the software in AmigaMINIX. They should be able to recover data which is unreadable on the Amiga, and write it out in a proper error-free MFM format. If anyone trys this and either succeeds or fails, please let me know. If all else fails, you could try asking The MINIX Centre to re-write the floppy for you. Andy Michael -- Andy Michael (eesrajm@cc.brunel.ac.uk) " Emulation is the sincerest 85 Hawthorne Crescent form of pottery." West Drayton Middlesex - William Frend De Morgan UB7 9PA