[sebhc] h17 and h8d disk images

Barry Watzman Watzman at neo.rr.com
Wed Sep 1 21:39:40 CDT 2004

You know, the H-8 disk controller was really simple.  It would not be that
hard to wire-wrap one.  The schematics are in the manual, which we have.

-----Original Message-----
From: sebhc at sebhc.org [mailto:sebhc at sebhc.org] On Behalf Of Dave Dunfield
Sent: Wednesday, September 01, 2004 10:29 PM
To: sebhc at sebhc.org
Subject: RE: [sebhc] h17 and h8d disk images

At 19:17 01/09/2004 -0700, you wrote:
>>From: "Barry Watzman" <Watzman at neo.rr.com>
>>Personally, if I was writing an image program, I'd record each track's
>>sectors in the order in which they physically occurred on the track AND
>>also record, in each sector's data contents, the track and sector number
>>recorded in that sector's header.
> Although, it is possible to acquire this information through
>the current H17 disk controller, my primary purpose was
>to move standard disk from machine to machine when I wrote
>the image transfer program. I realize that there could be
>all kinds of protection methods used. Trying to predict
>them all was not my intent. There are some that without
>knowing how it was done might not be reliably read with
>a one size-fits-all type program.
> If I was doing it over, I suspect that I might today have
>it a little more robust.

>From my point of view, the MOST important thing is that we
preserve the content of the disks - I'm not quite so concerned
about interleave and such, for two reasons:

1) Applicable to non-copy protected disks only (which appears to
   be the vast majority) - The data is the part that cannot be
   easily replaced - We can move things around, make our own disks,
   experiement with interleave etc. and make disks from the images
   in pretty much any way we like, however we HAVE TO HAVE the
   original data to do so.

2) I don't even HAVE a disk controller for my H8 (I'd REALLY like
   to find one if anyone happens to stumble on it) - As noted in a
   previous message, the emulator really doesn't care.

Even with the simple H8D format - just having that (and knowing that
it boots/runs fine on the emulator) provides me with the assurance I
need that this software will not be lost.

A slightly more complex format which includes the header information
(basically, record the positions of the sector pulses and ALL data
which occurs between them) would be a little more complete, and is
probably not a bad idea (I confess to not having looked in detail
at the .H17 format to see exactly what it records).

But as long as we have enough information to boot/run the software, I
am happy.

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.

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