Mail Archives: opendos/2000/10/31/00:11:24
----- Original Message -----
From: "Robert W Moss" <domanspc AT juno DOT com>
To: <opendos AT delorie DOT com>
Sent: Sunday, October 29, 2000 5:49 PM
Subject: Re: DRDOS FDISK
> Pat,
> Since you have been around since Bill Gates was in grade school, it is
I was around before he was born.
> funny that you don't know why the last cylinder of the HD was left out by
> the MSDOS FDisk program. Back in those days the hard disks heads
> stopped anywhere they were at when the computer was powered down, and
> they bounced and scraped along on your data. That's why the Park program
> was written, so the heads would travel to the last (unused) track on the
> last cylinder and any damage would not cause any damage to the usable
> parts of the disk.
That is baloney. There are several tracks beyond the last track. When you
park the heads, they retrack to the inner most part of the exposed platter.
Some drives such as Seagte had a cylinder beyond the last cylinder called
the CE track. This sometimes contained information on it by some
manufactures. I think it was Disk Manager that would allow you to format
this track and use it as a test track. This track is beyond the last
physical cylinder used. For example an ST251 had 820 cylinders if I remember
correctly and the CE cylinder was cylinder 821. DOS would only format 819
cylinders. And that is a fact. I still have my old ST251 that I RLL'd to get
about 64MB from. It is still a good drive. At first I thought maybe that is
where some drives put their bad track lists. Seagate never used a list on
the drive. It was printed on a label stuck to the top of the drive.
Some drive manufactures did use a bad track list on the drive and that mey
have been in the CE cylinder. Non MS filesystems will use all of the
cylinders. i.e. if I were to put the ST251 into this computer and FDISK it
with Linux FDISk it would use all 820 cylinders not just 819. That is a
fact.
> In some cases, there was some diagnostic data put on the disk by the
> manufacturer and this was put on the last cylinder. I believe I read
> that in one of my ancient (circa 198x) Peter Norton books.
That was the CE cylinder. It is one cylinder after the stated number of
cylinders for the drive. The book you are referring to must have been after
his first book "Inside the IBM PC" 1983, which I have a copy of, because
when he wrote this book, IBM did not yet have the XT. He only mentions hard
drives in this book.
> There was also the floppy drive thing where you could write to a 720k
> disk and format it as a 360k disk with the old 2.11 DOS. You could read
> the full 720k but not format the disk as 720. In later DOS versions you
> could still format a 720K disk as 360K but were also able to format them
> to 720k. I believe that was because IBM had not yet included the 720k
> capability in the BIOS until the AT was put out with 720K disks. I don't
> remember if it was 3.2 or 3.3 DOS which came with the AT.
That was probably a controller card that had it's own BIOS that allowed
connecting a 720k drive to it. I believe that DOS 3.1 was introduced with
the AT. I remeber reading that somewhere. Most of the stuff we had did have
3.2 and 3.3, so 3.1 was probably a short term version. I did not see all the
manuals on all of those old PCs and we may have had some with 3.1. I do know
that we had Compaq 286's that came with 3.1. I remember because I could not
find XCOPY and wondered why. XCOPY was not included in 3.1. We even had PCs
with DOS v1 and two full height floppy drives and they were still using them
when I left that company in 1990!
> There were also a lot of people about that time who cut an extra hole in
> 360k to make the computer think they were 1.2Mdisks and 720K disks were
You must be joking! Or is this some kind of test? There were no EXTRA
hole(s) in 1.2 diskettes. They are indentical to 360k. The only difference
is the media itself. You could not format a 360k to 1.2 mb without getting
tons of bad sectors. Yeah their were programs to make them 720k and 800k and
maybe other capacities. I tried some of those and lost data because of them.
I quit using them because of that. 400k formats worked okay.
> punched or drilled or burned to make the computer think they were 1.44Meg
> disks. There was a lot of stuff written in computer mags about data loss
> due to bad media on the reverse side of the disks, and there was also the
> problem of all those little microscopic bits from the drilling and
> punching operation getting caught by the heads and destroying data. I
This is partially true. You are mixing apples and oranges. The reverse side
thingy was what we called flippy. That is when you tried to use the reverse
side of a signle sided floppy. I did this a lot with my APPLE ][+ computer
and some diskettes work just fine. I still have a number of them that are
still readable.
> tried the 360k to 1.2Meg and used good BSF and Storage Master DSDD disks
> but I found out over half of my disks couldn't hold data on the back
> side. About 1993 the price of the 1.2Meg/1.44Meg disks dropped a lot ,
> so it didn't make sense anymore anyway.
I have no idea about the back side thing, but my experience was that the
inner tracks (on both sides) were not reliable. That is what some of the 720
and 800k programs would do, they would put 15 or 18 sectors on a track but
would not use about the last half of the 80 tracks, i.e. they only used the
first 40 or so tracks. However, after letting the diskettes sit for a while
(weeks or months) the information would be lost.
> Now I just buy my disks pre-formatted and never worry about it again
> unless I have to use Nortons Clean program on a diskette.
That is WIPEDISK. I find that Central Point BULKERAS is better. I would have
to check it out, but I believe all that Norton's does is rewrite the sectors
with whatever you tell it to or just defaults to 00 or F6. BULKERAS actually
erases the sector headers and everything on the floppy. Their is not sector
information or anything. Sometimes I had to do this when I copied APPLE copy
protacted diskettes on the IBM. So I use it whenever I want to completely
wipe everything off a diskette. Sometimes when DOS says a diskette has a bad
track zero, this is the only method that will work if the diskette can be
recovered and used. Most of the time nothing helps those and I throw them
away.
> You do have a lot of good knowledge and I have read most of the same
> stuff in my DOS manuals and in Upgrading and Repairing PCs by Scott
> Mueller and in PC Upgrade and Maintenance Guide by Marki Minassi.
I have never read those books. Actually, most of my knowledge of disks came
from when I was using my APPLE ][+ computer. APPLE included the DOS source
code in their manuals and the source code in the controller ROM. It
explained how DOS was loaded. I later got a book titled Beneath The APPLE
DOS. This explained everything about APPLE DOS for floppies. When I started
using IBM computers many years later, I picked up PC DOS very quickly. I
also read the IBM Technical Reference Manual for DOS 3.3. That is probably
one of the best manuals for DOS ever printed. I wish I had my own copy of
that manual so I could use it for reference. I do have copies of the PC and
XT manuals, but never got around to copying that one. It was always locked
up in an office when I worked night shifts or I would have a copy of it.
> I do really enjoy the traffic on the site but I wish the FLAMES could be
> cut down a little. Those FLAMING should remember that you should always
> use UPPER CASE when FLAMING. I also prefer "Expletive Deleted" or
> "Nixonism" to "C***" and other such annoyances, although there are over
> 150,000 other english words that could be used.
I try hard to just ignore the flaming and try not to add to it, but
ocassionally, I just have to put my 2c worth in. I have seen flaming threads
go on for a long time and consists of hundreds of messages. Not here but on
FIDO. What they should do is put FLAME in the subject line then you can tell
your reader not to dowmload them-:)-:)-:)
Pat
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