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Groups > comp.sys.ibm.ps2.hardware > #71531

-TC on A30 Re: ABIOSDSK.386

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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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Thread

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

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