5 Jul
2005
5 Jul
'05
6:41 p.m.
Hello all,
Believe it or not, I couldn't find this on google, so I humbly submit
it here....
Does anyone have a list of the built-in drive types from the original
IBM AT? I'd like the drive number, heads, cyls, and capacity if you
have the list. The setup program on the diagnostics disk only lets
you pick a type, but it does not tell you what the choices are...
Of course, I know that later computers came along with BIOSes that let
you see the drive types instead of picking one out of thin air, but I
don't know if these followed the AT choices...
Thanks!
Rich B.
5 Jul
5 Jul
7:06 p.m.
On Tue, 5 Jul 2005, Richard Beaudry wrote:
Does anyone have a list of the built-in drive types
from the original
IBM AT? I'd like the drive number, heads, cyls, and capacity if you
have the list. The setup program on the diagnostics disk only lets
you pick a type, but it does not tell you what the choices are...
http://www.msclub.ce.cctpu.edu.ru/bibl/PCB/ch23.htm#Heading18
Mike Loewen mloewen at cpumagic.scol.pa.us
The Dixie Lion Jazz Band http://ripsaw.cac.psu.edu/dixie.html
The B9 Robot Builders Club B9-0014 http://ripsaw.cac.psu.edu/~mloewen/B9/
Old Technology http://ripsaw.cac.psu.edu/~mloewen/Oldtech/
8:39 p.m.
Hello all,
Believe it or not, I couldn't find this on google, so I humbly submit
it here....
Does anyone have a list of the built-in drive types from the original
IBM AT? I'd like the drive number, heads, cyls, and capacity if you
I have a BIOS source listing that gives the hard disk parameter tables.
It's not the _original_ BIOS (it's the 1985 one), but I think earlier
ones just defined fewer drive types. Anyway :
No Cylinders Heads Write Precomp Landing Zone Sectors/track
1 306 4 128 306 17
2 615 4 300 615 17
3 615 6 300 615 17
4 940 8 512 940 17
5 940 6 512 940 17
6 615 4 none 615 17
7 462 8 256 511 17
8 733 5 none 733 17
9 900 15 none 901 17
10 820 3 none 820 17
11 855 5 none 855 17
12 855 7 none 855 17
13 306 8 128 319 17
14 733 7 none 733 17
15 ------- RESERVED -- Do not use ----------------------------
16 612 4 all 663 17
17 977 5 300 977 17
18 977 7 none 977 17
19 1024 7 512 1023 17
20 733 5 300 732 17
21 733 7 300 732 17
22 733 5 300 733 17
23 306 4 all 336 17
Guessing what the various drives were is left as an exercise for the
reader :-)
-tony
9:58 p.m.
On Tue, 2005-07-05 at 20:39 +0100, Tony Duell wrote:
I have a BIOS source listing that gives the hard disk
parameter tables.
It's not the _original_ BIOS (it's the 1985 one), but I think earlier
ones just defined fewer drive types. Anyway :
Home come entry 15 was reserved? (and why pick 15?)
cheers
J.
10:32 p.m.
New subject: DEC stuff on ebay (UK)
A PDP-11/03 chassis (same one as before I think, but cheaper):
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=96944&item…
435231&rd=1
A DECserver 200 (personally I'd like a 100 ...):
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=96944&item…
781703&rd=1
A MicroVAX 3100 of some sort, comes with tapes, some of which could do
with imaging:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=5786946507&rd=…
agename=STRK%3AMEWA%3AIT&rd=1
And finally, tonight's star prize, four VAX 6000-600s, fully loaded and,
as
a special bonus, a bunch of HSJs and cables:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=5216108968&rd=…
agename=STRK%3AMEWA%3AIT&rd=1
I know someone was interested in a VAX 6000 ....
Antonio
11:02 p.m.
New subject: DEC stuff on ebay (UK)
And finally, tonight's star prize, four VAX
6000-600s, fully loaded and,
as
a special bonus, a bunch of HSJs and cables:
Meltie's going to explode :)
--
adrian/witchy
Binary Dinosaurs creator/curator
www.binarydinosaurs.co.uk - the UKs biggest home computer collection?
11:28 p.m.
New subject: DEC stuff on ebay (UK)
On Tue, 2005-07-05 at 23:02 +0100, Witchy wrote:
I dunno, you could just about live inside four of those :)
And finally,
tonight's star prize, four VAX 6000-600s, fully loaded and,
as
a special bonus, a bunch of HSJs and cables:
Meltie's going to explode :) 
11:27 p.m.
New subject: DEC stuff on ebay (UK)
Jules Richardson wrote:
On Tue, 2005-07-05 at 23:02 +0100, Witchy wrote:
I dunno, you could just about live inside four of those :)
With the docs you could
make a nice roof for you new home.
And
finally, tonight's star prize, four VAX 6000-600s, fully loaded and,
as
a special bonus, a bunch of HSJs and cables:
Meltie's going to explode :) 
6 Jul
6 Jul
11:18 a.m.
New subject: DEC stuff on ebay (UK)
A MicroVAX 3100 of some sort, comes with tapes, some of which could do
with imaging:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=5786946507&rd=…
agename=STRK%3AMEWA%3AIT&rd=1
I've put a bid on these, they are located in the next street down from
me, I am going to take a look at them this week. I'll let you know
what's there, I was only really looking at the software and backup
tapes.
Dan
8:21 p.m.
Entry 15 was set special, so if a setup program wanted to
scan the table, and it could be a different size, it had a marker
to search for. Everyone skipped it so that you could either use
bios format programs, the IBM AT prep program for a geometry
from 0-14, or a program that was loaded from a floppy
with
the disk controller to format the drive.
The explanation claims that the table entry was used to indicate
special parameters, but I recall some bios programs that used
this, and the disks were not very happy to be moved to other
controller types.
Extended tables went from 16-40 usually. Int 41 is the pointer
to the table. It can be dumped using dos debug if the machine
is booted in real mode.
I found a nice reference for the old dos stuff here:
http://www.clipx.net/ng/
Jules Richardson wrote:
On Tue, 2005-07-05 at 20:39 +0100, Tony Duell wrote:
I have a BIOS source listing that gives the hard
disk parameter tables.
It's not the _original_ BIOS (it's the 1985 one), but I think earlier
ones just defined fewer drive types. Anyway :
Home come entry 15 was reserved? (and why pick 15?)
cheers
J. 
1:34 a.m.
At 01:41 PM 7/5/05 -0400, you wrote:
Hello all,
Believe it or not, I couldn't find this on google, so I humbly submit
it here....
Does anyone have a list of the built-in drive types from the original
IBM AT? I'd like the drive number, heads, cyls, and capacity if you
have the list. The setup program on the diagnostics disk only lets
you pick a type, but it does not tell you what the choices are...
Of course, I know that later computers came along with BIOSes that let
you see the drive types instead of picking one out of thin air, but I
don't know if these followed the AT choices...
They don't! They usually follow the AT types for the first ten or
fifteen or so but after that they differ AND the added settings are all
different in different clone BIOSs.
Joe
Thanks!
Rich B.
7 Jul
7 Jul
1:44 a.m.
On Tue, 5 Jul 2005 13:41:13 -0400
Richard Beaudry <richard.beaudry at gmail.com> wrote:
Hello all,
Believe it or not, I couldn't find this on google, so I humbly submit
it here....
Does anyone have a list of the built-in drive types from the original
IBM AT? I'd like the drive number, heads, cyls, and capacity if you
have the list. The setup program on the diagnostics disk only lets
you pick a type, but it does not tell you what the choices are...
Of course, I know that later computers came along with BIOSes that let
you see the drive types instead of picking one out of thin air, but I
don't know if these followed the AT choices...
As one suggestion, you do not need to use the original IBM Setup disk.
There are plenty of third-party MS-DOS utilties to do the AT Setup, and
I'm pretty certain some of them are more user friendly and include drive
topologies.
On this topic, I recently located an original IBM Monochrome monitor, so
for me it's now just a matter of pulling out the EGA Techref and
jumpering the IBM EGA card in my AT for EGA monochrome and plugging the
monitor and an original PC-AT 84 key keyboard in, and I can fire up the
AT I've been wanting to check out for over a year.
8:17 p.m.
On this topic, I recently located an original IBM
Monochrome monitor, so
for me it's now just a matter of pulling out the EGA Techref and
jumpering the IBM EGA card in my AT for EGA monochrome and plugging the
One thing a lot of people forget : There's a jumper on the board near the
DE9 connector which selects where pin 2 of said DE9 goes (LSB of one of
the colours for an EGA monitor, ground for an MDA or CGA monitor). If you
set that to the EGA position and then connect an MDA (or for that matter
CGA) monitor, you're shorting an output line to ground via the monitor
cable. It probably won't do any harm, but why risk it...
-tony
8 Jul
8 Jul
3:40 a.m.
On Thu, 7 Jul 2005 20:17:59 +0100 (BST)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
Yes, if I remember correctly, there are two jumper areas on the original
EGA card that need to be moved. I bought an EGA card years ago from a
second hand dealer and it came with the techref suppliment, which I
still have. Thanks for reminding me to be careful and doublecheck when
I get going on that AT.
I was probably one of the few people who ran EGA-Monochrome on an XT,
back when an XT was all I could afford. EGA-Monochrome was very well
supported in a few essential apps like Microsoft Word for DOS, and it
also gave a MUCH better video resolution for Windows 3.0 on a 9-pin mono
monitor than a Hercules card. Back in the days when I was too cheap to
buy an expensive EGA monitor and ran Windows on an 8088 machine...
Running EGA-monochrome kept me from wasting my time playing games, since
there was none, nadda, no support at all for gameplaying type graphics
on EGA-mono.
On this topic,
I recently located an original IBM Monochrome
monitor, so for me it's now just a matter of pulling out the EGA
Techref and jumpering the IBM EGA card in my AT for EGA monochrome
and plugging the
One thing a lot of people forget : There's a jumper on the board near
the DE9 connector which selects where pin 2 of said DE9 goes (LSB of
one of the colours for an EGA monitor, ground for an MDA or CGA
monitor). If you set that to the EGA position and then connect an MDA
(or for that matter CGA) monitor, you're shorting an output line to
ground via the monitor cable. It probably won't do any harm, but why
risk it...
-tony
23 Jul
23 Jul
4:33 a.m.
Scott Stevens wrote:
EGA-Monochrome was very well
supported in a few essential apps like Microsoft Word for DOS, and it
also gave a MUCH better video resolution for Windows 3.0 on a 9-pin mono
monitor than a Hercules card.
Huh? EGA mono is 640x350; Hercules is 720x348. You get more pixels with Hercules.
Running EGA-monochrome kept me from wasting my time
playing games, since
there was none, nadda, no support at all for gameplaying type graphics
on EGA-mono.
You didn't look hard enough ;-) There were at least 100 games of the adventure
or strategy variety that I remember specifically supporting EGA 640x350 mono.
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Want to help an ambitious games project? http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
5:11 a.m.
On Fri, 22 Jul 2005 22:33:21 -0500
Jim Leonard <trixter at oldskool.org> wrote:
Scott Stevens wrote:
For whatever reason, the drivers for Windows 3.0 make for a MUCH nicer
looking display with EGA monochrome than for a Hercules card. I can't
say why, but I distinctly remember this as being the case. It might
have more to do with the aspect ratio than the pixel count.
EGA-Monochrome was very well
supported in a few essential apps like Microsoft Word for DOS, and
it also gave a MUCH better video resolution for Windows 3.0 on a
9-pin mono monitor than a Hercules card.
Huh? EGA mono is 640x350; Hercules is 720x348. You get more pixels
with Hercules.
25 Jul
25 Jul
7:03 p.m.
Back in the day, I ran Windows 3.1 on a 12MHz 286, with a Hercules
card, and I still remember how vertically stretched the splash screen
looked on the Hercules display.
That thing was a sad mess - I had a EGA card and monitor I used for
color graphics, and a Hercules I used for Windows apps (for the higher
resolution)
Despite its quirks, I wish I never separated and sold that machine.
Thems whuz the daze...
On Jul 22, 2005, at 11:11 PM, Scott Stevens wrote:
On Fri, 22 Jul 2005 22:33:21 -0500
Jim Leonard <trixter at oldskool.org> wrote:
Scott Stevens wrote:
For whatever reason, the drivers for Windows 3.0 make for a MUCH nicer
looking display with EGA monochrome than for a Hercules card. I can't
say why, but I distinctly remember this as being the case. It might
have more to do with the aspect ratio than the pixel count.
EGA-Monochrome was very well
supported in a few essential apps like Microsoft Word for DOS, and
it also gave a MUCH better video resolution for Windows 3.0 on a
9-pin mono monitor than a Hercules card.
Huh? EGA mono is 640x350; Hercules is 720x348. You get more pixels
with Hercules.
8 Jul
8 Jul
2:34 p.m.
The scanning frequencies of the EGA and MDA cards should be real close (MDA outputs 348
lines of res, the EGA 350). You shouldn't have a problem there (I won't comment
about the jumpering/shorting though), but keep in mind the original IBM mono monitor was
very very touchy. If you plugged it into a CGA card, it was known to...ummm...explode...
I won't swear to it, but I had thought there was a way of configuring it specifically
for a mono monitor. Don't hold me to it though.
Tony Duell <ard at p850ug1.demon.co.uk> wrote:
On this topic, I recently located an original IBM
Monochrome monitor, so
for me it's now just a matter of pulling out the EGA Techref and
jumpering the IBM EGA card in my AT for EGA monochrome and plugging the
One thing a lot of people forget : There's a jumper on the board near the
DE9 connector which selects where pin 2 of said DE9 goes (LSB of one of
the colours for an EGA monitor, ground for an MDA or CGA monitor). If you
set that to the EGA position and then connect an MDA (or for that matter
CGA) monitor, you're shorting an output line to ground via the monitor
cable. It probably won't do any harm, but why risk it...
-tony
---------------------------------
Sell on Yahoo! Auctions - No fees. Bid on great items.
11 Jul
11 Jul
11:14 p.m.
The scanning frequencies of the EGA and MDA cards should be real close
(MDA outputs 348 lines of res, the EGA 350). You shouldn't have a
problem there (I won't comment about the jumpering/shorting though), but
keep in mind the original IBM mono monitor was very very touchy. If you
plugged it into a CGA card, it was known to...ummm...explode...
That's going a bit far. It's very easy to burn out the horizontal output
transistor and maybe associated components, but it won't explode.
There is no horizontal osciallator in the MDA (5151) monitor. The Hsync
line goes to the base of the horizontal driver transistor, the collector
of which is transformer-coupled to the base of the horizontal output
transistor. You can therefore attempt to drive the horizontal system at
just about any frequency, but if the horizontal output stage is driven
way off resonance (e.g. using the CGA frequncies), it will do nasty things.
I won't swear to it, but I had thought there was a way of configuring
it specifically for a mono monitor. Don't hold me to it though.
There is. There are switch settings for the EGA card to drive the MDA
monitor, CGA monitor, or EGA monitor (the latter can operate at 2
different horizontal frequencies). The reason I mentioned the jumper link
is that a lot of people forget to set that correctly when linking to a
CGA or MDA monitor.
-tony
12 Jul
12 Jul
2:33 a.m.
On Mon, 11 Jul 2005 23:14:15 +0100 (BST)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
Its my understanding (but I've only seen it as a rumor, not as hard
technical fact) that the reason the original IBM Monitors plug into the
PC Power Supply and not directly into an outlet is that they were
vulnerable to damage (probably the same horizontal drive problem) if
left powered on independent of the PC.
I at one point had an original IBM monitor that had a direct power cord
connector and understood at the time that it was one of the very early
monitors for this reason. (I also at one point had an IBM PC-1, the
first-generation IBM PC, detectable from later versions by it's four
rows of 16K chips and the powersupply and I/O channel backplates being
painted black. I grow angry just thinking about the row with the
landlord that led to me giving that machine up)
The scanning frequencies of the EGA and MDA cards should be real
close (MDA outputs 348 lines of res, the EGA 350). You shouldn't
have a problem there (I won't comment about the jumpering/shorting
though), but keep in mind the original IBM mono monitor was very
very touchy. If you plugged it into a CGA card, it was known
to...ummm...explode...
That's going a bit far. It's very easy to burn out the horizontal
output transistor and maybe associated components, but it won't
explode.
There is no horizontal osciallator in the MDA (5151) monitor. The
Hsync line goes to the base of the horizontal driver transistor, the
collector of which is transformer-coupled to the base of the
horizontal output transistor. You can therefore attempt to drive the
horizontal system at just about any frequency, but if the horizontal
output stage is driven way off resonance (e.g. using the CGA
frequncies), it will do nasty things.
I won't swear to it, but I had thought there was a way of
configuring
it specifically for a mono monitor. Don't hold me to it though.
There is. There are switch settings for the EGA card to drive the MDA
monitor, CGA monitor, or EGA monitor (the latter can operate at 2
different horizontal frequencies). The reason I mentioned the jumper
link is that a lot of people forget to set that correctly when linking
to a CGA or MDA monitor.
-tony
7:45 p.m.
Its my understanding (but I've only seen it as a
rumor, not as hard
technical fact) that the reason the original IBM Monitors plug into the
PC Power Supply and not directly into an outlet is that they were
vulnerable to damage (probably the same horizontal drive problem) if
left powered on independent of the PC.
I've heard that rumour too, but I can't understand why, after looking at
the schematics. The horizontal drive is transformer-coupled, so it
doesn't matter if the input gets stuck high or low, it still won't turn
on the output transsitor.
I at one point had an original IBM monitor that had a direct power cord
connector and understood at the time that it was one of the very early
The CGA and EGA nonitors of course connect separately to the mains. The
MDA monitor has a built-in power cable ending in an IEC plug that would,
in theroy, fit into a normal 'kettle lead'. AFAIK all were built like that.
I am using a 5151 now. On the grounds it doesn't have a power switch of
its own, I plug it into the outlet on the system unit PSU. I suspect,
though, it would do no damage to power it separately.
-tony
10:20 p.m.
originally the IBM division that did terminals owned the PC and that
may have had something to do with it. It was later during a squabble
over it's impact on system sales that it finally broke loosed into a separate
division.
It could have had to do with UL approvals as well, though I have no
basis to prove that.
Jim
Tony Duell wrote:
Its my
understanding (but I've only seen it as a rumor, not as hard
technical fact) that the reason the original IBM Monitors plug into the
PC Power Supply and not directly into an outlet is that they were
vulnerable to damage (probably the same horizontal drive problem) if
left powered on independent of the PC.
I've heard that rumour too, but I can't understand why, after looking at
the schematics. The horizontal drive is transformer-coupled, so it
doesn't matter if the input gets stuck high or low, it still won't turn
on the output transsitor.
13 Jul
13 Jul
3:30 a.m.
older monitors were not meant to be left on w/o a
video signal driving it is my understanding. I used to
have an Ikegami 19" fixed frequency workstation
monitor that went kaput possibly due to this reason.
But it was of a later vintage...might have just been
due to crap out.
--- jim stephens <jwstephens at msm.umr.edu> wrote:
originally the IBM division that did terminals owned
the PC and that
may have had something to do with it. It was later
during a squabble
over it's impact on system sales that it finally
broke loosed into a separate
division.
It could have had to do with UL approvals as well,
though I have no
basis to prove that.
Jim
Tony Duell wrote:
why, after looking at
____________________________________________________
Start your day with Yahoo! - make it your home page
http://www.yahoo.com/r/hs
> Its my understanding (but I've only seen
it as a
rumor, not as hard
> technical fact) that the reason the original
IBM
Monitors plug into the
> PC Power Supply and not directly into an
outlet
is that they were
> vulnerable to damage (probably the same
horizontal drive problem) if
left
powered on independent of the PC.
I've heard that rumour too, but I can't understand the schematics. The horizontal drive is
transformer-coupled, so it
doesn't matter if the input gets stuck high
or
low, it still won't turn
on the output transsitor.
7115
days inactive
7135
days old
22 comments
14 participants
participants (14)
-
a.carlini＠ntlworld.com -
ard＠p850ug1.demon.co.uk -
bfranchuk＠jetnet.ab.ca -
chenmel＠earthlink.net -
chrism3667＠yahoo.com -
fireflyst＠earthlink.net -
julesrichardsonuk＠yahoo.co.uk -
jwstephens＠msm.umr.edu -
mloewen＠cpumagic.scol.pa.us -
richard.beaudry＠gmail.com -
rigdonj＠cfl.rr.com -
trixter＠oldskool.org -
williams.dan＠gmail.com -
witchy＠binarydinosaurs.co.uk