PS/2s nicer than expected; some questions

From: Russ Blakeman <>
Date: Fri Mar 26 14:20:39 1999

Mark Gregory wrote:

> Over the weekend I acquired some interesting PS/2 machines: a PS/2 P70 386
> portable, and a PS/2 Model 95 XP 486 server. This was my first experience
> with the PS/2 family, and I was pleasantly surprised. From what I remember
> when PS/2s were new, the media savaged them, mainly due to high price and
> the incompatibility with all existing ISA cards, RAM, etc.

Any big corporate venture that's non-standard is ravaged by the media. Somehow
they have made themselves out to be the experts just because they have a
channel to the rest of the world. They are different but very nice once you get
the jist of them, epecially the newer 95xx series machines.

> I was impressed with the build quality and design of the machines (the
> power supply in the M95 XP486 for example: undo one butterfly screw and the
> whole thing swivels out, allowing easy access to the drive bays) and with
> the ease of configuration of Microchannel cards - better Plug and Play than
> with many peripherals on Win 9x machines.

Well except for diconnecting the power cables to the drives in some instances
as well as unplugging the unit or there won't be any swinging out going to
happen. Not Plug-n-Pray so much as Plug-n-Go Find the ADF file. This is also an
eay thing once you find and bookmark the proper sites of storage for the
ADF/ADC files.

> Some questions:
> 1) Why did Microchannel fail so completely? From a user point of view it
> seems quite nice.

It really didn't. It evolved to EISA combining the best of both MCA and ISA.

> 2) Can MFM or IDE drives be used with an ESDI controller, or do the drives
> have to be ESDI drives?

Nope. ESDI is similar to SCSI in that the controller is only a host adapter,
not an actual controller like MFM and RLL. This allows you to have the drive's
parameters queryed by the host adapter and set auto-magically rather than
digging up a bunch of specs and crosing your fingers that they'll work.

> 3) Anybody know if the 486DX33 on the processor board can be replaced with
> an Overdrive chip to make it at least a 486/66; or, does IBM still run
> their parts depot in Boulder for old machines?

Better to look around for an AMD 5x86 upgrade and make it a Pentium class
machine. They can be gotten for around $50 in used form. OR you can get one of
the processor complex cards from another model 8590 or 8595 (they're the same
except for the case) and use it. I don't think you can use one from a 9590 or
9595 since they've changed and added a few things.
As for the P70 there is an IBM FRU (field replaceable unit) that is made for
the 70 and 80 that makes it a 486 but it won't physically fit. You can use one
of the many 386-486 upgrades available. My wife's 8573, aka P70, is a 486 with
Win95 and 16mb ram. I used a $25 "MakeIt 486" that plugged right in place of
the 386 chip.

> 3) I'm having some trouble with the P70. Originally, it wouldn't boot at
> all. I ran the diagnostics from the Reference Disk, and all tests were
> passed. I re-ran the Auto Configuration with no errors. I installed PC-DOS
> 6.3, and formatted the built-in HD at the same time. Everything seems fine,
> but the system won't boot from the hard drive alone. If I boot with a
> floppy in the drive, I can access the HD and run programs off of it. But
> without a floppy, nothing works. Any ideas?

You can do a "low level format" (a hardware level format) by going to the
opening menu of the reference disk and pressing CTRL-A and then going to hard
drive preparation. Once this passes and completes, reboot with a DOS disk and
put a partition on the drive and then reboot and format using FORMAT C::/S to
transfer the system files. You may also need to replace the drive if it doesn't
come around. I've had one or two over the period of all my PS/2 ventures come
up bad for whatever reason. Usually the MFM 20 and 30 mb ones do that
though.They have a "type" number on the ID label and a narrower bus connection
than the full width that the 70 uses. The P70 uses the ESDI "MCA" drives that
autopark and should talk to the host adapter on their own.

If worse comes to worse email me directly, I have all sorts of machines and
parts. Also the IBM "HMM" or hardare maintenance manual for all the machines
you have are online at but please note
that the P70 is not in the PS/2 manual but rather in one of the other manuals -
see the manual descriptions. The L40/SX is also listed in that series for
anyone that might need it.
Received on Fri Mar 26 1999 - 14:20:39 GMT

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