20 Jun
2001
20 Jun
'01
3:31 p.m.
I've got some 8" disks that are apparently double density (the
manufacturer label says so). I thought they were Intel ISIS formatted
disks (which Eric Smith said would make them M2FM and uncompatible with
anything other than an Intel MDS development machine) but I'm not so sure,
since I can't seem to access any on the two Intel MDS systems I have set
up.
Both machines have Shugart 801 drives in them, and after doing some web
research, I've come to find out they are single-density only. This would
probably explain why I am not able to access these disks on these
machines.
The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
anything). If this is the case, and they were formatted on an Intel MDS
(and therefore M2FM), and since they are double-density, then I may not be
able to read them with the machines I have.
However, I want to check their format on some CP/M machine and see if
perhaps I can read them. If so, then they are probably more standard DD
formatted diskettes, maybe even CP/M since that is what I was told they
are.
If they are in a standard DD format, and I have a computer that can boot a
DD CP/M system master, could I then pop these disks in the drive and do a
DIR to see if I get a directory?
For those who've used these before: when I put any of the disks in
question in the drive, the drive seems to seek for a few seconds, then
goes off for a split second, back on again for half a second, then off
(and the system crashes). The normal boot sequence for a (single density)
system disk is, upon reboot the disk seeks for a few seconds, then stops
for a split second, then starts seeking/reading for a few more seconds and
the ISIS prompt comes up.
It seems the system is trying to read the double density disks and just
not seeing anything intelligible and crashes. With single density
non-system diskettes, the machines will come up with something like "NOT A
SYSTEM DISK".
Suggestions appreciated.
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
20 Jun
20 Jun
4:51 p.m.
On Wed, 20 Jun 2001, Vintage Computer Festival wrote:
I've got some 8" disks that are apparently double density (the
manufacturer label says so). I thought they were Intel ISIS formatted
disks (which Eric Smith said would make them M2FM and uncompatible with
anything other than an Intel MDS development machine) but I'm not so sure,
since I can't seem to access any on the two Intel MDS systems I have set
up.
Both machines have Shugart 801 drives in them, and after doing some web
research, I've come to find out they are single-density only. This would
probably explain why I am not able to access these disks on these
machines.
The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
anything). If this is the case, and they were formatted on an Intel MDS
(and therefore M2FM), and since they are double-density, then I may not be
able to read them with the machines I have.
However, I want to check their format on some CP/M machine and see if
perhaps I can read them. If so, then they are probably more standard DD
formatted diskettes, maybe even CP/M since that is what I was told they
are.
If they are in a standard DD format, and I have a computer that can boot a
DD CP/M system master, could I then pop these disks in the drive and do a
DIR to see if I get a directory?
Sellam, there is not really a 'standard DD format' in CP/M. There are
so many variations that if you tried that it would be a matter of purest
coincidence if it could read them.
For those who've used these before: when I put any
of the disks in
question in the drive, the drive seems to seek for a few seconds, then
goes off for a split second, back on again for half a second, then off
(and the system crashes). The normal boot sequence for a (single density)
system disk is, upon reboot the disk seeks for a few seconds, then stops
for a split second, then starts seeking/reading for a few more seconds and
the ISIS prompt comes up.
It seems the system is trying to read the double density disks and just
not seeing anything intelligible and crashes. With single density
non-system diskettes, the machines will come up with something like "NOT A
SYSTEM DISK".
Suggestions appreciated.
You could mail me a couple and let me see if I can read them. Can't do
m2mfm, but most other.
- don
Sellam Ismail
Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
21 Jun
21 Jun
3:12 a.m.
Sellam,
I'm a bit rusty on my Intels but I *think* the original MDS 200
machines used single sided and single density. However they could be
upgraded to DS-SD and/or DS-DD. So your disks could be any of several
different formats. My 235 has the DS-DD upgrade and I'm running ISIS-II.
It's still set up and it was running the last time I tried it a couple of
years ago. If you want to sent your disks to me I'll see what I can find
out about them.
I was going to E-mail you about something else. After getting this
MDS-800, I realized that some of the bits and peices that I saw at a
scrapper's are part of an 800. There's not much left of it except the
housing but you mentioned that some of the case parts on yours were
missing/damaged. If you'll sent me a list of what you need, I'll see if I
can find it in the pile. I think the floppy drives are still in the box
but they're almost certainly 801s.
Joe
At 08:31 PM 6/20/01 -0700, you wrote:
I've got some 8" disks that are apparently
double density (the
manufacturer label says so). I thought they were Intel ISIS formatted
disks (which Eric Smith said would make them M2FM and uncompatible with
anything other than an Intel MDS development machine) but I'm not so sure,
since I can't seem to access any on the two Intel MDS systems I have set
up.
Both machines have Shugart 801 drives in them, and after doing some web
research, I've come to find out they are single-density only. This would
probably explain why I am not able to access these disks on these
machines.
The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
anything). If this is the case, and they were formatted on an Intel MDS
(and therefore M2FM), and since they are double-density, then I may not be
able to read them with the machines I have.
However, I want to check their format on some CP/M machine and see if
perhaps I can read them. If so, then they are probably more standard DD
formatted diskettes, maybe even CP/M since that is what I was told they
are.
If they are in a standard DD format, and I have a computer that can boot a
DD CP/M system master, could I then pop these disks in the drive and do a
DIR to see if I get a directory?
For those who've used these before: when I put any of the disks in
question in the drive, the drive seems to seek for a few seconds, then
goes off for a split second, back on again for half a second, then off
(and the system crashes). The normal boot sequence for a (single density)
system disk is, upon reboot the disk seeks for a few seconds, then stops
for a split second, then starts seeking/reading for a few more seconds and
the ISIS prompt comes up.
It seems the system is trying to read the double density disks and just
not seeing anything intelligible and crashes. With single density
non-system diskettes, the machines will come up with something like "NOT A
SYSTEM DISK".
Suggestions appreciated.
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
7:40 a.m.
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9:07 a.m.
Tony's right about the Shugart 801's. Drives don't determine the modulation
technique used to record the data. The "density" refers to the number of bits
per linear inch on the track. Since that's really not an adequate measure in
this context, its sensibly applied analog would be bits per revolution. The
head/media combination determines the number of flux changes per inch (fcpi) and
single-density uses two flux changes per bit, while double density uses only one
(not exactly, but close enough). If the drive can manage to swap the flux
direction quickly enough, which the '801 clearly can, then it's a double-density
capable drive, which it is. Confusion arises from the fact that, while the '801
can read/write double density, its board-resident "data separator" can't.
Also,
while the older '901 wasn't commonly used for double density, it could manage
MFM if one used 250ns of write precomp. The '801 required only 160-180 ns.
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, June 21, 2001 1:40 PM
Subject: Re: Question about Intel disk formats
I've got some 8" disks that are apparently double density (the
manufacturer label says so). I thought they were Intel ISIS formatted
disks (which Eric Smith said would make them M2FM and uncompatible with
anything other than an Intel MDS development machine) but I'm not so sure,
since I can't seem to access any on the two Intel MDS systems I have set
up.
Intel certainly made an M2FM disk controller for the MDS800 (I have one
here in my MDS). It was couple of Multibus boards with Intel 3000 series
bit-slice chips on them.
But I believe they also made a 'normal' single-density disk controller
board (FM, IBM3740-like format). Maybe that's what was used to record them.
FWIW, many floppies say double density on the label. This means the media
is capable of handling double-densisty recording. It doesn't mean that
they can't also be used for single density. Unless the label written by
whoever formated and used the disks says 'double density' I wouldn't
assume that they were.
Both machines have Shugart 801 drives in them,
and after doing some web
research, I've come to find out they are single-density only. This would
This is news to me (and to all the machines I have with 801 drives that
quite happily do double density recording). These drives do have an
internal clock/data separator which is single density only, but most
people didn't use that (the raw data is available on the interface
connector as usual). And then you can most certainly use these drives for
MFM or M2FM (or whatever) recording.
probably explain why I am not able to access
these disks on these
machines.
The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
.HEX probably means an Intel Hex format file. Used on Intel development
systems, CP/M machines, many EPROM/microcontroller programmers, and a lot
of other places.
-tony
12:47 p.m.
What I read on the Web was that the first Shugart 801's could not
read/write DD, no matter what controller was attached to it. However,
later-manufactured 801's could handle both SD and DD.
Edwin
At 03:07 PM 6/21/2001 -0600, you wrote:
Tony's right about the Shugart 801's. Drives
don't determine the modulation
technique used to record the data. The "density" refers to the number of
bits
per linear inch on the track. Since that's really
not an adequate measure in
this context, its sensibly applied analog would be bits per revolution. The
head/media combination determines the number of flux changes per inch
(fcpi) and
single-density uses two flux changes per bit, while
double density uses
only one
(not exactly, but close enough). If the drive can
manage to swap the flux
direction quickly enough, which the '801 clearly can, then it's a
double-density
capable drive, which it is. Confusion arises from the
fact that, while
the '801
can read/write double density, its board-resident
"data separator" can't.
Also,
while the older '901 wasn't commonly used for
double density, it could manage
MFM if one used 250ns of write precomp. The '801 required only 160-180 ns.
Dick
12:55 p.m.
If it is CP/M format, the first track should be SD, whether or not the
disk is formatted DD. That's how it is in the CP/M systems I have. I
figure you should at least be able to read the first track and hopefully
there would be a signature of what machine it's from. What I would not
know is what interleave factor to use for the sector ordering; it seems to
vary from machine to machine. Start with the original IBM SSSD structure.
Edwin
At 08:31 PM 6/20/2001 -0700, you wrote:
The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
anything). If this is the case, and they were formatted on an Intel MDS
(and therefore M2FM), and since they are double-density, then I may not be
able to read them with the machines I have.
However, I want to check their format on some CP/M machine and see if
perhaps I can read them. If so, then they are probably more standard DD
formatted diskettes, maybe even CP/M since that is what I was told they
are.
Suggestions appreciated.
Sellam Ismail Vintage Computer
Festival
---------------------------------------------------------------------------
---
International Man of Intrigue and Danger
http://www.vintage.org
1:24 p.m.
On Thu, 21 Jun 2001, Edwin P. Groot wrote:
If it is CP/M format, the first track should be
SD, whether or not the
disk is formatted DD. That's how it is in the CP/M systems I have. I
Many of the best systemes are that way, but there are literally thousands
of disk formats that aren't.
figure you should at least be able to read the first
track and hopefully
there would be a signature of what machine it's from. What I would not
know is what interleave factor to use for the sector ordering; it seems to
vary from machine to machine. Start with the original IBM SSSD structure.
In addition to the sector sequence, for anything other than SSSD, you also
have to contend with different sector sizes, and as a result, different
numbers of sectors per track.
--
Fred Cisin cisin(a)xenosoft.com
XenoSoft http://www.xenosoft.com
PO Box 1236 (510) 558-9366
Berkeley, CA 94701-1236
22 Jun
22 Jun
2:20 a.m.
If it is CP/M standard format, it should be IBM3740 formatted single-density.
There are lots of other formats that work under CP/M though. I've never seen a
format with an identifying signature that was recognizable on another system.
However, since different systems have different controllers, they use different
approaches to using that controller. Interleaving rates are a common
inconsistency between systems, but 4 is a common interleave for double-density
with a 4 MHz Z80. You can get some insight into the way data layout is
implemented if you look at the directory track (track 2). If there's a
recognizable file name, then you can rigorously search for the data that
comprises that file by searching the entire diskette. If you don't have the
interleave, it doesn't matter, since directory entries are in 128-byte sectors,
derived from the Single Density format. All you need is the name of a widely
known standard file, e.g. PIP.COM. You then find the file contents, bit by bit,
and keep records of where you found each 128-byte block of the file, and then
divine the sector layout from that. It's not fun, but you only have to do it
once.
Good luck!
Dick
----- Original Message -----
From: "Edwin P. Groot" <epgroot(a)ucdavis.edu>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, June 21, 2001 6:55 PM
Subject: Re: Question about Intel disk formats
If it is CP/M format, the first track should be
SD, whether or not the
disk is formatted DD. That's how it is in the CP/M systems I have. I
figure you should at least be able to read the first track and hopefully
there would be a signature of what machine it's from. What I would not
know is what interleave factor to use for the sector ordering; it seems to
vary from machine to machine. Start with the original IBM SSSD structure.
Edwin
At 08:31 PM 6/20/2001 -0700, you wrote:
The disks I am trying to access are supposedly CP/M, but the labelling
indicates they were perhaps used on an Intel development system (they have
filenames on the label with ".HEX" file types; this may not mean
anything). If this is the case, and they were formatted on an Intel MDS
(and therefore M2FM), and since they are double-density, then I may not be
able to read them with the machines I have.
However, I want to check their format on some CP/M machine and see if
perhaps I can read them. If so, then they are probably more standard DD
formatted diskettes, maybe even CP/M since that is what I was told they
are.
Suggestions appreciated.
Sellam Ismail Vintage Computer
Festival
---------------------------------------------------------------------------
---
International Man of Intrigue and Danger
http://www.vintage.org
8901
days inactive
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8 comments
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participants (7)
-
ard＠p850ug1.demon.co.uk -
cisin＠xenosoft.com -
donm＠cts.com -
edick＠idcomm.com -
epgroot＠ucdavis.edu -
rigdonj＠intellistar.net -
vcf＠siconic.com