Re: Reading 5.25" Pascal 1.3 on a Mac

[THE MARVELOUS MERV <u1002942@warwick.net>]

On Thu, 2 Jan 1997, John Moreno wrote:

> Sheldon Simms <sheldon@atlcom.net> wrote:
> 
> ] In article <199701010738012226980@roxboro-185.interpath.net>,
> ] phenix@interpath.com (John Moreno) wrote:
> ] 
> ] > For the last week or so I've been working on a program, similar
> ] > Apple File Exchange, that allow me to read Pascal 1.3 3.5" disk.
> ] > What I'd like to know is if anybody knows if something similar might
> ] > be possible with the 5.25" disk?
> ] > 
> ] None.
> ] 
> ] Well actually, Apple did make a PC-compatible 5.25 drive for the Mac
> ] specifically for the purpose of reading MS-DOS disks, but that
> ] wouldn't help your project since the PC-style 5.25 drive couldn't read
> ] an Apple Pascal disk.
> 
> How sure are you of this?  That's what I thought at first about the 3.5
> disk, until I tried - now it's working quite well. What's the difference
> between a disk for the Apple II and a PC disk?  I've used 5.25 disk out
> of the same box on both.  I'm not SURE that it can be done, and I would
> appreciate hearing from somebody that would be willing to try.  All they
> would need to do is email me their address and I would send them a
> diskette which they could try to read with a disk editor - FEdit, Norton
> Util. or something similar.

John --

ALL 3.5" drives ( except 400k drives ) have physically 2 heads -- top and
bottom.  Apple or IBM style.  Most 3.5" disks that I know about are double
- sided, double density ( at least ).  5 1/4" disks are usually at a
minimum double sided double density.  IBM style 5 1/4"ers also have 2
heads -- top and bottom.  Apple 5 1/4"ers only have the bottom head.  This
is why you have to cut a notch in the other side of an Apple disk and
physically _Flip The Disk_ to use the second side; and you don't have to
do this to use the second side of an IBM style disk.  Sure, a PC disk
drive can read an Apple format disk -- but only if you are a very serious
drive mechanism programmer type, and can tell the computer to ignore all
the data coming in from the top head, and somehow coerce the drive into
reading directory information from just the bottom head . . . . 

There may have been specailty stuff for the Apple || to support IBM style
disks, and special add - ons ( either Apple - styled hardware or REALLY
sophisticated software ) for PC's to read Apple disks.  But it is NOT as
easy as you imply. 

If you have more questions, ask Nathan ( I'm sure he'll direct you to 
this rather complete FAQ ).

Hope I've Helped --

Merv

Tom Murphy                     also         Commander Merv sutai - Jare'achan
THE MARVELOUS MERV                          Chief of Sciences, "USS _Fury_"
Pack Ape Extraordinaire                     Chief of CompOps
Sometimes Herald - Mage                     Chief of TroubleShooting
MarvMerv@Warwick.NET                        Treknologist@Warwick.NET