5 Jan
2004
5 Jan
'04
9:15 a.m.
On Jan 5, 15:02, Gene Buckle wrote:
Me, I want to know how they make an FM/MFM drive read
a GCR disk...
It's not a drive issue, it's a controller issue. The bits on the disk
are just bits on a disk... just alternating magnetic poles. There's
nothing strange or different about the heads or amplifiers on an Apple,
Commodore, or Amiga drive.
--
Pete Peter Turnbull
Network Manager
University of York
5 Jan
5 Jan
9:54 a.m.
On Mon, 5 Jan 2004, Pete Turnbull wrote:
On Jan 5, 15:02, Gene Buckle wrote:
... but the controller is ALSO FM/MFM. THAT is the "impossible" part.
hint: disrupt in mid-read by messing with drive select
and some drives work easier than others for it. For example,
with the Apple Turnover, Tandon TM100 drives worked well,
but Teac 55's would often not work without some minor mods.
Long ago, I tried unsuccessfully to implement the technique.
And then more recently, I tried some software that purported
to do it. Also unsuccessfully.
But neither of my attempts were in sufficient depth to state
that the technique can't work - my congratulations to the guy
who succeeded!
And once there is a successful track read, parsing sectors
and working out the DIRectory is straight-forward.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
Me, I want to know how they make an FM/MFM drive
read a GCR disk...
It's not a drive issue, it's a controller issue. The
bits on the disk
are just bits on a disk... just alternating magnetic poles. There's
nothing strange or different about the heads or amplifiers on an Apple,
Commodore, or Amiga drive. 
10 a.m.
So where do we d/l this magical software?!?!?
Curt
----- Original Message -----
From: "Fred Cisin" <cisin(a)xenosoft.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk(a)classiccmp.org>
Sent: Monday, January 05, 2004 6:54 PM
Subject: Re: reading apple ii disks with PCs: it WORKS !!!
On Mon, 5 Jan 2004, Pete Turnbull wrote:
On Jan 5, 15:02, Gene Buckle wrote:
... but the controller is ALSO FM/MFM. THAT is the "impossible" part.
hint: disrupt in mid-read by messing with drive select
and some drives work easier than others for it. For example,
with the Apple Turnover, Tandon TM100 drives worked well,
but Teac 55's would often not work without some minor mods.
Long ago, I tried unsuccessfully to implement the technique.
And then more recently, I tried some software that purported
to do it. Also unsuccessfully.
But neither of my attempts were in sufficient depth to state
that the technique can't work - my congratulations to the guy
who succeeded!
And once there is a successful track read, parsing sectors
and working out the DIRectory is straight-forward.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
Me, I want to know how they make an FM/MFM drive
read a GCR disk...
It's not a drive issue, it's a controller issue. The
bits on the disk
are just bits on a disk... just alternating magnetic poles. There's
nothing strange or different about the heads or amplifiers on an Apple,
Commodore, or Amiga drive. 
1:43 p.m.
On Jan 5, 15:02, Gene Buckle wrote:
:r/drive/controller/
:)
g.
Me, I want to know how they make an FM/MFM drive
read a GCR disk...
It's not a drive issue, it's a controller issue. The bits on the disk
are just bits on a disk... just alternating magnetic poles. There's
nothing strange or different about the heads or amplifiers on an Apple,
Commodore, or Amiga drive.
7657
days inactive
7657
days old
3 comments
4 participants
participants (4)
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cisin＠xenosoft.com -
curt＠atarimuseum.com -
geneb＠deltasoft.com -
pete＠dunnington.u-net.com