Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/13/84; site intelca.UUCP
Path: utzoo!linus!philabs!prls!amdimage!amdcad!decwrl!sun!idi!intelca!glen
From: glen@intelca.UUCP (Glen Shires)
Newsgroups: net.micro.pc,net.micro.apple
Subject: Re: Re: Want to read Apple II disk on IBM PC
Message-ID: <41@intelca.UUCP>
Date: Mon, 19-Aug-85 20:05:19 EDT
Article-I.D.: intelca.41
Posted: Mon Aug 19 20:05:19 1985
Date-Received: Fri, 23-Aug-85 20:29:02 EDT
References: <125@well.UUCP> <576@mmintl.UUCP>
Organization: Intel, Santa Clara, Ca.
Lines: 37
Xref: linus net.micro.pc:4755 net.micro.apple:1780

> 
> *
> 	Software to read Apple disks on IBM PCs does not exist, since Apple
> does not use the index hole (I agree that this is a real drag).  Special
> hardware is therefore required.  There is a board by Quadram which lets you
> ....
> 	*************************************************
> 	*	Jeff Miller				*
> 	*	Multimate International Corp.		*
> 	*  UUCP:					*
> 	* ...!seismo!utah-cs!utah-gr!pwa-b!mmintl!jeffm *
> 	*************************************************

Yes, the Apple doesn't use the index hole (that's why you can flip
floppies without cutting out a new index hole).  Still this is a
problem one could work around.

But the differences go much deeper than that.  Apple uses special
hardware (the infamous Woz machine) and software to read/write the
disk (See "Beneath Apple DOS" for a great explanation).  IBM-PC on
the other hand uses a "standard" disk controller chip (NEC uPD 765)
which has the formats built-in (no whizzy software).

Although nothing matches at any level (directories, track/sector
markings, etc.), the bottom line is that these could all be worked
around except for one especially subtle gremlin:

The way in which the data and clock is mixed onto the disk is completely
different.  The PC uses standard MFM, the Apple uses no clocks but
restricts the data to certain patterns.


-- 
^ ^    Glen Shires, Intel, Santa Clara, Ca.
O O     Usenet: {ucbvax!amd,pur-ee,hplabs}!intelca!glen
 >      ARPA:   "amd!intelca!glen"@BERKELEY
\-/    --- stay mellow