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ABIOSDSK.386: 32-bit disk access for your PS/2's MFM and ESDI drives

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  ABIOSDSK.386: 32-bit disk access for your PS/2's MFM and ESDI drives "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 02:48 +0000
    W95 and SCSI Louis Ohland <ohland@charter.net> - 2026-08-07 22:06 -0500
      Re: W95 and SCSI "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 03:10 +0000
        Re: W95 and SCSI Louis Ohland <ohland@charter.net> - 2026-08-07 22:33 -0500
          Re: W95 and SCSI "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 14:33 +0000
    FD had 32-bit BDA? Louis Ohland <ohland@charter.net> - 2026-08-07 22:08 -0500
      Re: FD had 32-bit BDA? "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 03:11 +0000
      Re: FD had 32-bit BDA? "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 03:12 +0000
    These are not the hard drives you are looking for Re: ABIOSDSK.386 Louis Ohland <ohland@charter.net> - 2026-08-08 07:03 -0500
      Re: These are not the hard drives you are looking for Re: ABIOSDSK.386 "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 14:27 +0000
        -TC on A30 Re: ABIOSDSK.386 Louis Ohland <ohland@charter.net> - 2026-08-08 09:44 -0500
          Re: -TC on A30 Re: ABIOSDSK.386 "Josh Rodd" <joshua.at.rodd.dot.us@rodd.us> - 2026-08-08 14:55 +0000

#71517 — ABIOSDSK.386: 32-bit disk access for your PS/2's MFM and ESDI drives

Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.

This has been about 35 years in coming, ever since as a sprightly 11
year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
the "32-bit Disk Access", despite me barely understanding what was even
for. Of course, we now know that that means you can do things like open
a couple DOS windows on your 2MB machine and listen to the fixed disk
(or, more likely, a hard drive, since this wasn't happening on real IBM
computers with real IBM fixed disk adapters/A) thrash like crazy.

Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
program is included which tries to really exercise the disk and get
Windows' multitasking really crankin' with a couple DOS windows open.

Download it for yourself at:
https://github.com/sbooks-org/ABIOSDSK386
Direct link for 720kB floppy image, because how else would you get it on
your PS/2?
https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG

No warranty is implied, particularly given this is the kind of code
whose failure mode will mean you get to reformat your fixed disk and
reinstall everything.

I plan to do SCSI support next (it's easier than it sounds; it's just
another ABIOS interface). Can someone remind me what the state of
Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
PS/2 SCSI adapter is?

[toc] | [next] | [standalone]

#71519 — W95 and SCSI

Unal Z and WBST snuck out for some really good smokes. They aren't 
taking any text messages.

https://ardent-tool.com/utils/#Win_Utils

SPOCK206.ZIP SPOCK206 Driver for Windows 95/98 by Unal Z (info)
https://ardent-tool.com/IBM_SCSI/spock206.html

SPOCK2NT.ZIP SPOCK206 Driver for Windows NT by Unal Z (info)
https://ardent-tool.com/IBM_SCSI/spock206.html

AHA206.ZIP AHA-1640 Windows 95/98 driver by Unal Z (info)
https://ardent-tool.com/SCSI/aha206.html

Josh Rodd wrote:
> Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> 
> This has been about 35 years in coming, ever since as a sprightly 11
> year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> the "32-bit Disk Access", despite me barely understanding what was even
> for. Of course, we now know that that means you can do things like open
> a couple DOS windows on your 2MB machine and listen to the fixed disk
> (or, more likely, a hard drive, since this wasn't happening on real IBM
> computers with real IBM fixed disk adapters/A) thrash like crazy.
> 
> Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> program is included which tries to really exercise the disk and get
> Windows' multitasking really crankin' with a couple DOS windows open.
> 
> Download it for yourself at:
> https://github.com/sbooks-org/ABIOSDSK386
> Direct link for 720kB floppy image, because how else would you get it on
> your PS/2?
> https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> 
> No warranty is implied, particularly given this is the kind of code
> whose failure mode will mean you get to reformat your fixed disk and
> reinstall everything.
> 
> I plan to do SCSI support next (it's easier than it sounds; it's just
> another ABIOS interface). Can someone remind me what the state of
> Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> PS/2 SCSI adapter is?
> 

[toc] | [prev] | [next] | [standalone]

#71522 — Re: W95 and SCSI

Aha... I recall those drivers now, and they are state of the art.

Was there ever an ABIOS disk driver for Windows 95? I know NT had one,
called, well, ABIOSDSK.SYS.

ABIOSDSK.386 should not be considered to be "high performance" just yet.
It does its fair share of double buffering to avoid the pitfalls of DMA.

Louis Ohland <ohland@charter.net> wrote:
> Unal Z and WBST snuck out for some really good smokes. They aren't 
> taking any text messages.
> 
> https://ardent-tool.com/utils/#Win_Utils
> 
> SPOCK206.ZIP SPOCK206 Driver for Windows 95/98 by Unal Z (info)
> https://ardent-tool.com/IBM_SCSI/spock206.html
> 
> SPOCK2NT.ZIP SPOCK206 Driver for Windows NT by Unal Z (info)
> https://ardent-tool.com/IBM_SCSI/spock206.html
> 
> AHA206.ZIP AHA-1640 Windows 95/98 driver by Unal Z (info)
> https://ardent-tool.com/SCSI/aha206.html
> 
> Josh Rodd wrote:
> > Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> > PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> > 
> > This has been about 35 years in coming, ever since as a sprightly 11
> > year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> > the "32-bit Disk Access", despite me barely understanding what was even
> > for. Of course, we now know that that means you can do things like open
> > a couple DOS windows on your 2MB machine and listen to the fixed disk
> > (or, more likely, a hard drive, since this wasn't happening on real IBM
> > computers with real IBM fixed disk adapters/A) thrash like crazy.
> > 
> > Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> > and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> > thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> > card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> > program is included which tries to really exercise the disk and get
> > Windows' multitasking really crankin' with a couple DOS windows open.
> > 
> > Download it for yourself at:
> > https://github.com/sbooks-org/ABIOSDSK386
> > Direct link for 720kB floppy image, because how else would you get it on
> > your PS/2?
> > https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> > 
> > No warranty is implied, particularly given this is the kind of code
> > whose failure mode will mean you get to reformat your fixed disk and
> > reinstall everything.
> > 
> > I plan to do SCSI support next (it's easier than it sounds; it's just
> > another ABIOS interface). Can someone remind me what the state of
> > Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> > PS/2 SCSI adapter is?
> > 

[toc] | [prev] | [next] | [standalone]

#71526 — Re: W95 and SCSI

 From a cursory surf, I'd say no.

My SWAG would be looking at the NT miniport... Not what you wandted to 
hear...

Josh Rodd wrote:
> Aha... I recall those drivers now, and they are state of the art.
> 
> Was there ever an ABIOS disk driver for Windows 95? I know NT had one,
> called, well, ABIOSDSK.SYS.
> 
> ABIOSDSK.386 should not be considered to be "high performance" just yet.
> It does its fair share of double buffering to avoid the pitfalls of DMA.
> 
> Louis Ohland <ohland@charter.net> wrote:
>> Unal Z and WBST snuck out for some really good smokes. They aren't
>> taking any text messages.
>>
>> https://ardent-tool.com/utils/#Win_Utils
>>
>> SPOCK206.ZIP SPOCK206 Driver for Windows 95/98 by Unal Z (info)
>> https://ardent-tool.com/IBM_SCSI/spock206.html
>>
>> SPOCK2NT.ZIP SPOCK206 Driver for Windows NT by Unal Z (info)
>> https://ardent-tool.com/IBM_SCSI/spock206.html
>>
>> AHA206.ZIP AHA-1640 Windows 95/98 driver by Unal Z (info)
>> https://ardent-tool.com/SCSI/aha206.html
>>
>> Josh Rodd wrote:
>>> Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
>>> PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
>>>
>>> This has been about 35 years in coming, ever since as a sprightly 11
>>> year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
>>> the "32-bit Disk Access", despite me barely understanding what was even
>>> for. Of course, we now know that that means you can do things like open
>>> a couple DOS windows on your 2MB machine and listen to the fixed disk
>>> (or, more likely, a hard drive, since this wasn't happening on real IBM
>>> computers with real IBM fixed disk adapters/A) thrash like crazy.
>>>
>>> Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
>>> and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
>>> thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
>>> card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
>>> program is included which tries to really exercise the disk and get
>>> Windows' multitasking really crankin' with a couple DOS windows open.
>>>
>>> Download it for yourself at:
>>> https://github.com/sbooks-org/ABIOSDSK386
>>> Direct link for 720kB floppy image, because how else would you get it on
>>> your PS/2?
>>> https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
>>>
>>> No warranty is implied, particularly given this is the kind of code
>>> whose failure mode will mean you get to reformat your fixed disk and
>>> reinstall everything.
>>>
>>> I plan to do SCSI support next (it's easier than it sounds; it's just
>>> another ABIOS interface). Can someone remind me what the state of
>>> Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
>>> PS/2 SCSI adapter is?
>>>
> 
> 

[toc] | [prev] | [next] | [standalone]

#71530 — Re: W95 and SCSI

Louis Ohland <ohland@charter.net> wrote:
>  From a cursory surf, I'd say no.
> 
> My SWAG would be looking at the NT miniport... Not what you wandted to 
> hear...

It has been around 29 years since I engaged in the dark art of NT
programming as a young intern for the remnants of a once-great American
manufacturer, now splattered around the world like a nebula after a
supernova... and, indeed, I was once spending lots of time studying blue
screens, attaching kernel debuggers, and even restarting the kernel -
and all this on PS/2 P75 (the system under test). It had an 8MB Cumulus
card, which was unreliable in the P75 (they probbably only tested it on
Model 70/80 386) and would caused random memory errors after a few
hours, which perfectly duplicated problems happening in the field.

At this point, WFW3.11 and whatever came before is what fascinates me.
Other quixotic quests on deck are building a PC/AT BIOS with ABIOS
support; 32-bit disk access for the PS/2 SCSI adapter; getting AIX PS/2
actually usable in 86Box; fixing the problems where BASIC/BASICA don't
work in a Win 386 Enhanced DOS box; and, of course, improving the Mod.
50/60/70/80 BIOSes as discussed previously.

[toc] | [prev] | [next] | [standalone]

#71520 — FD had 32-bit BDA?

Joshua, IIRC the FD MCS-700 had 32-bit BDA.

Josh Rodd wrote:
> Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> 
> This has been about 35 years in coming, ever since as a sprightly 11
> year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> the "32-bit Disk Access", despite me barely understanding what was even
> for. Of course, we now know that that means you can do things like open
> a couple DOS windows on your 2MB machine and listen to the fixed disk
> (or, more likely, a hard drive, since this wasn't happening on real IBM
> computers with real IBM fixed disk adapters/A) thrash like crazy.
> 
> Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> program is included which tries to really exercise the disk and get
> Windows' multitasking really crankin' with a couple DOS windows open.
> 
> Download it for yourself at:
> https://github.com/sbooks-org/ABIOSDSK386
> Direct link for 720kB floppy image, because how else would you get it on
> your PS/2?
> https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> 
> No warranty is implied, particularly given this is the kind of code
> whose failure mode will mean you get to reformat your fixed disk and
> reinstall everything.
> 
> I plan to do SCSI support next (it's easier than it sounds; it's just
> another ABIOS interface). Can someone remind me what the state of
> Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> PS/2 SCSI adapter is?
> 

[toc] | [prev] | [next] | [standalone]

#71523 — Re: FD had 32-bit BDA?

It sure did... FASTDISK, I believe. By the time I was an adolescent
snotling, I acquired it along with an MCS-600 and finally got to click
that 32-bit Disk Access button.

Not that it really mattered since I spent most of my time booted into an
actual 32-bit operating system (you know, the one that had all-16-bit
disk adapter device drivers...)

Louis Ohland <ohland@charter.net> wrote:
> Joshua, IIRC the FD MCS-700 had 32-bit BDA.
> 
> Josh Rodd wrote:
> > Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> > PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> > 
> > This has been about 35 years in coming, ever since as a sprightly 11
> > year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> > the "32-bit Disk Access", despite me barely understanding what was even
> > for. Of course, we now know that that means you can do things like open
> > a couple DOS windows on your 2MB machine and listen to the fixed disk
> > (or, more likely, a hard drive, since this wasn't happening on real IBM
> > computers with real IBM fixed disk adapters/A) thrash like crazy.
> > 
> > Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> > and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> > thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> > card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> > program is included which tries to really exercise the disk and get
> > Windows' multitasking really crankin' with a couple DOS windows open.
> > 
> > Download it for yourself at:
> > https://github.com/sbooks-org/ABIOSDSK386
> > Direct link for 720kB floppy image, because how else would you get it on
> > your PS/2?
> > https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> > 
> > No warranty is implied, particularly given this is the kind of code
> > whose failure mode will mean you get to reformat your fixed disk and
> > reinstall everything.
> > 
> > I plan to do SCSI support next (it's easier than it sounds; it's just
> > another ABIOS interface). Can someone remind me what the state of
> > Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> > PS/2 SCSI adapter is?
> > 

[toc] | [prev] | [next] | [standalone]

#71524 — Re: FD had 32-bit BDA?

It sure did... FASTDISK, I believe. By the time I was an adolescent
snotling, I acquired it along with an MCS-600 and finally got to click
that 32-bit Disk Access button.

Not that it really mattered since I spent most of my time booted into an
actual 32-bit operating system (you know, the one that had all-16-bit
disk adapter device drivers...)

Louis Ohland <ohland@charter.net> wrote:
> Joshua, IIRC the FD MCS-700 had 32-bit BDA.
> 
> Josh Rodd wrote:
> > Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> > PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> > 
> > This has been about 35 years in coming, ever since as a sprightly 11
> > year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> > the "32-bit Disk Access", despite me barely understanding what was even
> > for. Of course, we now know that that means you can do things like open
> > a couple DOS windows on your 2MB machine and listen to the fixed disk
> > (or, more likely, a hard drive, since this wasn't happening on real IBM
> > computers with real IBM fixed disk adapters/A) thrash like crazy.
> > 
> > Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> > and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> > thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> > card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> > program is included which tries to really exercise the disk and get
> > Windows' multitasking really crankin' with a couple DOS windows open.
> > 
> > Download it for yourself at:
> > https://github.com/sbooks-org/ABIOSDSK386
> > Direct link for 720kB floppy image, because how else would you get it on
> > your PS/2?
> > https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> > 
> > No warranty is implied, particularly given this is the kind of code
> > whose failure mode will mean you get to reformat your fixed disk and
> > reinstall everything.
> > 
> > I plan to do SCSI support next (it's easier than it sounds; it's just
> > another ABIOS interface). Can someone remind me what the state of
> > Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> > PS/2 SCSI adapter is?
> > 

[toc] | [prev] | [next] | [standalone]

#71527 — These are not the hard drives you are looking for Re: ABIOSDSK.386

Someone has to fill in for our missing pedantic Brit.

My understanding is the DBA-ESDI isn't ESDI. Chances are that IBM 
appropriated "ESDI", trying to spiff-up the Integrated Drive used on the 
50z, 70, P70, and the early Model 90 [infamous -402].

My dark, inscrutable goal is to use the DBA-ESDI sockets for plug-in IDE 
controllers. My kontuzion lies in the fact that the Integrated Drive has 
it's own BIOS [or so I think], so the system doesn't need to support the 
DBA-ESDI drive... ?

IBM DBA-ESDI Hard Drives
https://ardent-tool.com/storage/DBA_ESDI.html

Direct Bus Attachment Pinout
https://ardent-tool.com/storage/DBA_ESDI.html#Pinout

PS. Yes, the DBA-Socket is a stripped-down 16-bit slot. IIRC, it lacks 
DMA. -BUT- it exists... The 50/70/90 were designed as a cable-less 
systems. Some kompromises as to storage speed, but a PIO device on the 
DBA-ESDI _should_ have comparable performance to the stock DBA-ESDI.


Josh Rodd wrote:
> Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> 
> This has been about 35 years in coming, ever since as a sprightly 11
> year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> the "32-bit Disk Access", despite me barely understanding what was even
> for. Of course, we now know that that means you can do things like open
> a couple DOS windows on your 2MB machine and listen to the fixed disk
> (or, more likely, a hard drive, since this wasn't happening on real IBM
> computers with real IBM fixed disk adapters/A) thrash like crazy.
> 
> Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> program is included which tries to really exercise the disk and get
> Windows' multitasking really crankin' with a couple DOS windows open.
> 
> Download it for yourself at:
> https://github.com/sbooks-org/ABIOSDSK386
> Direct link for 720kB floppy image, because how else would you get it on
> your PS/2?
> https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> 
> No warranty is implied, particularly given this is the kind of code
> whose failure mode will mean you get to reformat your fixed disk and
> reinstall everything.
> 
> I plan to do SCSI support next (it's easier than it sounds; it's just
> another ABIOS interface). Can someone remind me what the state of
> Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> PS/2 SCSI adapter is?
> 

[toc] | [prev] | [next] | [standalone]

#71529 — Re: These are not the hard drives you are looking for Re: ABIOSDSK.386

Thank you. My understanding is they are "true" IDE - they might have
some ESDI electronics IBM had lying around and "present" as the ESDI
controller, but, well, they're just like ATA, except this isn't an ATA
attachment, it's an MCA attachment. Perhaps it should be called MCAA.

It certainly does carry DMA - see the "ARB" pins. The IBM MFM and ESDI
controllers both used DMA (unlike inferior designs found in ISA
machines), and as attested by how my driver has to be careful not to run
into the usual "DMA in protected mode" type of problems.

Ultimately the McIDE controller could probably be adapted to this socket
- however, the McIDE does *not* present IBM ESDI/A or IBM MFM/A... and
there's no way to get a ROM in the DBA socket. I don't see anywhere that
responds to memory. I mean, I guess it could respond to 16-bit memory
acccesses and put ROM in the first 64KB of memory... not useful.

Louis Ohland <ohland@charter.net> wrote:
> Someone has to fill in for our missing pedantic Brit.
> 
> My understanding is the DBA-ESDI isn't ESDI. Chances are that IBM 
> appropriated "ESDI", trying to spiff-up the Integrated Drive used on the 
> 50z, 70, P70, and the early Model 90 [infamous -402].
> 
> My dark, inscrutable goal is to use the DBA-ESDI sockets for plug-in IDE 
> controllers. My kontuzion lies in the fact that the Integrated Drive has 
> it's own BIOS [or so I think], so the system doesn't need to support the 
> DBA-ESDI drive... ?
> 
> IBM DBA-ESDI Hard Drives
> https://ardent-tool.com/storage/DBA_ESDI.html
> 
> Direct Bus Attachment Pinout
> https://ardent-tool.com/storage/DBA_ESDI.html#Pinout
> 
> PS. Yes, the DBA-Socket is a stripped-down 16-bit slot. IIRC, it lacks 
> DMA. -BUT- it exists... The 50/70/90 were designed as a cable-less 
> systems. Some kompromises as to storage speed, but a PIO device on the 
> DBA-ESDI _should_ have comparable performance to the stock DBA-ESDI.
> 
> 
> Josh Rodd wrote:
> > Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
> > PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
> > 
> > This has been about 35 years in coming, ever since as a sprightly 11
> > year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
> > the "32-bit Disk Access", despite me barely understanding what was even
> > for. Of course, we now know that that means you can do things like open
> > a couple DOS windows on your 2MB machine and listen to the fixed disk
> > (or, more likely, a hard drive, since this wasn't happening on real IBM
> > computers with real IBM fixed disk adapters/A) thrash like crazy.
> > 
> > Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
> > and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
> > thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
> > card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
> > program is included which tries to really exercise the disk and get
> > Windows' multitasking really crankin' with a couple DOS windows open.
> > 
> > Download it for yourself at:
> > https://github.com/sbooks-org/ABIOSDSK386
> > Direct link for 720kB floppy image, because how else would you get it on
> > your PS/2?
> > https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
> > 
> > No warranty is implied, particularly given this is the kind of code
> > whose failure mode will mean you get to reformat your fixed disk and
> > reinstall everything.
> > 
> > I plan to do SCSI support next (it's easier than it sounds; it's just
> > another ABIOS interface). Can someone remind me what the state of
> > Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
> > PS/2 SCSI adapter is?
> > 

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#71531 — -TC on A30 Re: ABIOSDSK.386

Looking at the DBA-ESDI header pin-out, A30 is -TC

Huh.

Josh Rodd wrote:
> Thank you. My understanding is they are "true" IDE - they might have
> some ESDI electronics IBM had lying around and "present" as the ESDI
> controller, but, well, they're just like ATA, except this isn't an ATA
> attachment, it's an MCA attachment. Perhaps it should be called MCAA.
> 
> It certainly does carry DMA - see the "ARB" pins. The IBM MFM and ESDI
> controllers both used DMA (unlike inferior designs found in ISA
> machines), and as attested by how my driver has to be careful not to run
> into the usual "DMA in protected mode" type of problems.
> 
> Ultimately the McIDE controller could probably be adapted to this socket
> - however, the McIDE does *not* present IBM ESDI/A or IBM MFM/A... and
> there's no way to get a ROM in the DBA socket. I don't see anywhere that
> responds to memory. I mean, I guess it could respond to 16-bit memory
> acccesses and put ROM in the first 64KB of memory... not useful.
> 
> Louis Ohland <ohland@charter.net> wrote:
>> Someone has to fill in for our missing pedantic Brit.
>>
>> My understanding is the DBA-ESDI isn't ESDI. Chances are that IBM
>> appropriated "ESDI", trying to spiff-up the Integrated Drive used on the
>> 50z, 70, P70, and the early Model 90 [infamous -402].
>>
>> My dark, inscrutable goal is to use the DBA-ESDI sockets for plug-in IDE
>> controllers. My kontuzion lies in the fact that the Integrated Drive has
>> it's own BIOS [or so I think], so the system doesn't need to support the
>> DBA-ESDI drive... ?
>>
>> IBM DBA-ESDI Hard Drives
>> https://ardent-tool.com/storage/DBA_ESDI.html
>>
>> Direct Bus Attachment Pinout
>> https://ardent-tool.com/storage/DBA_ESDI.html#Pinout
>>
>> PS. Yes, the DBA-Socket is a stripped-down 16-bit slot. IIRC, it lacks
>> DMA. -BUT- it exists... The 50/70/90 were designed as a cable-less
>> systems. Some kompromises as to storage speed, but a PIO device on the
>> DBA-ESDI _should_ have comparable performance to the stock DBA-ESDI.
>>
>>
>> Josh Rodd wrote:
>>> Presenting ABIOSDSK.386: 32-bit disk access finally gets here for your
>>> PS/2 with gigantic, clanking MFM drives and irreplaceable ESDI drives.
>>>
>>> This has been about 35 years in coming, ever since as a sprightly 11
>>> year old I was miffed that my fancy PS/2 P70 just wouldn't let me click
>>> the "32-bit Disk Access", despite me barely understanding what was even
>>> for. Of course, we now know that that means you can do things like open
>>> a couple DOS windows on your 2MB machine and listen to the fixed disk
>>> (or, more likely, a hard drive, since this wasn't happening on real IBM
>>> computers with real IBM fixed disk adapters/A) thrash like crazy.
>>>
>>> Nonetheless, here it is. It is based on IBM2ADSK.ADD from the OS/2 DDK
>>> and WDCTRL from the Windows 3.1 DDK. So far, testing has been really
>>> thorough: I tested it on 86Box with a Type 2 Model 80, ESDI adapter
>>> card, PC DOS 3.30, 4MB and 2MB configurations, Windows 3.1. A test suite
>>> program is included which tries to really exercise the disk and get
>>> Windows' multitasking really crankin' with a couple DOS windows open.
>>>
>>> Download it for yourself at:
>>> https://github.com/sbooks-org/ABIOSDSK386
>>> Direct link for 720kB floppy image, because how else would you get it on
>>> your PS/2?
>>> https://github.com/sbooks-org/ABIOSDSK386/releases/download/v0.90/ABIOSDSK.IMG
>>>
>>> No warranty is implied, particularly given this is the kind of code
>>> whose failure mode will mean you get to reformat your fixed disk and
>>> reinstall everything.
>>>
>>> I plan to do SCSI support next (it's easier than it sounds; it's just
>>> another ABIOS interface). Can someone remind me what the state of
>>> Windows 95 support for ABIOS disk adapters (MFM, ESDI, etc.) and the
>>> PS/2 SCSI adapter is?
>>>
> 
> 

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#71533 — Re: -TC on A30 Re: ABIOSDSK.386

Louis Ohland <ohland@charter.net> wrote:
> Looking at the DBA-ESDI header pin-out, A30 is -TC
> 
> Huh.

A34 is M/-IO, , but with only A0-A15, it wouldn't be able to be a memory
slave for anything other than 0-64K.

The DBA ESDI card (for the 50Z?) had ROM on it, probably for this exact
reason.

Note that if you design a CompactFlash, etc. adapter for this, as long
as it does translation to "speak" ESDI or MFM, the PS/2's BIOS will
support it. This would be harder than it sounds since that means DMA.

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