Path: utzoo!attcan!uunet!world!decwrl!apple!olivea!oliveb!felix!reynolds From: reynolds@felix.UUCP (David Lee Reynolds) Newsgroups: comp.sys.cbm Subject: Re: 1581 disk drive Message-ID: <152053@felix.UUCP> Date: 5 Oct 90 15:38:26 GMT References: <2025@ac.dal.ca> <1990Oct1.222319.23869@alchemy.chem.utoronto.ca> <14378.2707ee38@max.u.washington.edu> Reply-To: reynolds@felix.UUCP (David Lee Reynolds) Organization: FileNet Corp., Costa Mesa, CA Lines: 41 In article <14378.2707ee38@max.u.washington.edu> scott@max.u.washington.edu writes: >In article <1990Oct1.222319.23869@alchemy.chem.utoronto.ca>, mroussel@alchemy.chem.utoronto.ca (Marc Roussel) writes: >> The reason that you can't read/write IBM disks with a 1541 (and conversely >> that it works with both 1571's and 1581's) is that IBM uses a file >> storage scheme alien to the 1541 (but which has been built in to the >> other two drives along with the usual Commodore formats). When I worked for a company called A.D.C. (Applied Data Communications), it was one of mu duties to test the "High-Speed" disk copiers. We supported ALL formats. You could take a data disk from the Commode to say an IBM, or an apple data disk to commode. The trick in reading a C-64 "1541" disk on your IBM is, your IBM (DOS) program must be told to ignore the "Index Pulse" (from the disk drive), because the 1541 HAS NO WAY OF KNOWING WHERE THE INDEX HOLE IS! (Which by the way is also true of Apple disks too). Commodore never installed the Index opto's, though they did include the cutouts in the drive design. That is why the speed of the 1541's motor is very important, because it depends on that time constant to format the disk... >I think it has to do more with the fact that the 1541 has only one >read/write head, and so it can read/write one side of the disk at a time. Old (I mean real old) IBM's had single sided drives, and as far as I know the subsequent versions of IBM DOS still support reading of said disks. (Humm, a concept that Commodore should learn, can you say down-ward compatibility??? Sure I new you could)... >> Marc R. Roussel >> mroussel@alchemy.chem.utoronto.ca > >Sincerely, >Scott K. Stephen *************************************************************************** * FileNet has no official opinion toward Disks! | Birds of a feather, * *--------------------------------------------------| flock together, over * * 1 message in rec.birds is worth 200 in rec.pets! | MY just-washed car! * *-------------------------------------------------------------------------* * Please give full direct return paths in any correspondence, Felix does * * not support back-bone addresses... Thank you... David Lee Reynolds * * (oliveb,hplabs,spsd,legs,zardoz,sco,tgate,ccicpg,dhw68k)!felix!reynolds * ***************************************************************************