Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!husc6!mit-eddie!uw-beaver!tektronix!tekcrl!tekfdi!videovax!stever From: stever@videovax.Tek.COM (Steven E. Rice, P.E.) Newsgroups: comp.sys.amiga Subject: Re: Reading MacDisks on Amiga Message-ID: <4391@videovax.Tek.COM> Date: Thu, 14-May-87 10:28:27 EDT Article-I.D.: videovax.4391 Posted: Thu May 14 10:28:27 1987 Date-Received: Sat, 16-May-87 13:03:12 EDT References: <8705080543.AA18112@cory.Berkeley.EDU> <112@l5comp.UUCP> <122@l5comp.UUCP> <18746@sun.uucp> Reply-To: stever@videovax.Tek.COM (Steven E. Rice, P.E.) Organization: Tektronix Television Systems, Beaverton, Oregon Lines: 35 Summary: More information needed. Recently, there have been a number of articles about this subject (see the "References" line), but some information has been missing. Given that the Mac disks rotate at 400-600 rpm (?) and are recorded at single- density rates, how fast would the bits come by on an Amiga? How fast would they come by on the innermost track? How fast would they come by on the outermost track? The reason for the question is that if the bits are recorded in a fashion that would cause them to come by about 4 usec apart at 300 rpm, it might be possible to read them as if they were 2 usec apart and then compensate in software for the drift that would occur as they were read either faster or slower than 4 usec. Another consideration is the response of the phase-locked loop (PLL) in the Amiga drive to off-speed bits. Can data be recovered (at least to the nearest 2 usec) even when the PLL is not locked? If it is possible to read the disk and get the raw bits to the nearest 2 usec (out of approximately 4 usec) then it should be possible to decode the data in software, compensating for the timing uncertainties. It might not be possible to write a disk for a Mac, but perhaps it would be possible to read the entire disk. Steve Rice ----------------------------------------------------------------------------- Copyright 1987 by Steven E. Rice, P.E. All Rights Reserved. This material may be redistributed only where such redistribution is without charge and without restrictions on further redistribution. Incorporation of this material in a compilation or other collective work constitutes permission from the intermediary to all recipients to freely redistribute the entire collection. All other uses are prohibited. ----------------------------------------------------------------------------- new: stever@videovax.tv.Tek.com old: {decvax | hplabs | ihnp4 | uw-beaver | cae780}!tektronix!videovax!stever