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From: acm@bu-cs.BU.EDU (ACM)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Any way to read/write Apple disks on IBM PC's?
Message-ID: <16100@bu-cs.BU.EDU>
Date: Tue, 17-Nov-87 20:37:53 EST
Article-I.D.: bu-cs.16100
Posted: Tue Nov 17 20:37:53 1987
Date-Received: Fri, 20-Nov-87 03:31:30 EST
References: <1364@mind.UUCP>
Reply-To: madd@bucsf.bu.edu
Followup-To: madd@bucsf.bu.edu
Organization: Boston University ACM
Lines: 47
Keywords: desparation

In article <1364@mind.UUCP> romero@mind.UUCP (Antonio Romero) writes:
>Anyone out there remember a product on the market quite some time ago
>which supposedly allowed one to read and write Apple II 5 1/4'' disks 
>on an IBM PC? I'm doing some cross development from an IBM PC to an
>Apple and am getting tired of sending my executables over a 9600 baud
>serial line every time I make a minor bug fix...
>I spend about half of my work day waiting for these things to go through.
>If anyone knows anything about such a product please send e-mail to 
>romero@mind.Princeton.EDU or romero@psycho.Princeton.EDU.  Please
>mail rather than post, since I'm almost never on these days...

I think that this actually might be a good thing to post about.

I do, indeed, remember a product that allowed you to transfer files
between an IBM PC and an Apple.  It was basically a controller card
for a Disk II and software to run it.  I cannot remember who put it
out or how much it cost, or even if the company that made them is
still in business.  Perhaps another netter has better information.

Someone is undoubtably going to say "well why not just use the drive
in the PC, with special software?".  Before they do, here's why you
can't.

The PC drives use MFM format, a way of putting the signal on the disk
(related to the FM signal used by radios).  Apple drives use a format
called GCD.  They are not compatible.  Now there's some interesting
stuff about that.  GCD format (at least in my experience) is somewhat
more reliable than either MFM or FM.  It's somewhat more complicated
to work with, however.  Anyone looking through the Apple DOS 3.3 or
ProDos code will agree with me there :-). I can't remember a whole lot
about either method but if you check out the Byte magazine issue that
was devoted to disks, there was considerable information in there.
This issue was a couple of years ago but should be easy to find by
either inspection of the issues or through the microfiche
cross-reference that every library seems to have nowadays.

Anyway, because of this difference in basic format, there is no way
either type of drive can read the other.  You need both a different
drive and a different controller, which is somewhat expensive.  Also,
there is limited demand -- how many people actually need to do this
sort of thing?  My guess is it's not that many so either the price
will be high or the company will be gone.  Good luck, though.

Hope this is informative and maybe it'll even help someone.

jim frost
madd@bucsf.bu.edu