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IBM 4956 Series I System


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  IBM 4956 Series I System by Bill Degnan - 05/18/2005 11:02

I have an IBM 4956 Series I System as described below (circa 1976-83). I have limited
experience with this era IBM and will gladly except assistance in the mean time I will slowly work to restore its function. I was told that it was operational when taken off line 20 years ago and appears to have been stored adequately. Assembled the system is
housed in two 6-foot rack cabinets with a total weight of 600-800lbs If you want it you will have to come to the Landenberg, PA USA which is on the extreme south-eastern tip of the state, about 10 miles from I-95 where Maryland meets Delaware. Bring a truck.

I can provide pictures or additional details upon request.

qty) description
2) 6' IBM 4997 Rack Units with shelves to house the processor and peripherals.
1) IBM 4956 Processor (see for German
equivalent pic of control panel) See also below.
1) Cambex Corp Model 80810 2-tape drive storage device (no tapes)
1) IBM 4962 8" disk drive (w/ 3 boxes of software)
1) IBM 4967 Hard drive (69kg)
1) IBM 4963 Hard drive (55kg)
1) IBM 4963A Hard drive (55kg)
1) IBM 4978 display station and keyboard. Not confident in display, unsure how to test.
12) Series I system software/hardware manuals "standard 3-ring binder sized"
20) Series I system software/hardware manuals (tall, blue, with IBM written on them)
There is documentation for all components, plus service logs, software documentation, installation instructions, etc. Pretty complete.

Misc. papers and other documentation and receipts.

3 boxes of IBM software on 8" disks, including diagnostics for hardware.
1 box of cables and jacks for additional display stations/terminals
1 box of printer ribbons (no printer)

product literature and period IBM sales circulars, etc.

* The 4956 Processor is full of the appropriate cards for the peripherals (hard drives,
tape drive, terminals, etc.) The system appears to have been upgraded at least once. I
have been able to cable up most peripherals to the matching processor cards. I do not
plan to power up the system at this time. I have cleaned each subsystem, but overall it
was "clean enough" already. Most of the wear is on the rack unit, dings and the like.

Overall condition is OK. Some dust removed.

Email billdeg at aol dot com.

  IBM Series 1 Project Update by Bill Degnan - 01/07/2008 22:37
Click here to see pictures of the IBM Series 1 in its new home. Most important I have the proper power to complete the restoration process.


  Booting an IBM 4956 by Bill Degnan - 05/03/2008 10:04
I have power now, and I have turned on the main CPU and disk drive. Booting an IBM 4956 with 4978 monitor and 4962 drive unit (Series 1 / Series I core unit)

I am starting to imagine ways to use the 4956 as a super expensive weak personal computer.

Currently the unit is not cabled up, but I have a pretty good idea of what goes where. But that can be dangerous. Better find out for sure.

NEXT: Learn more about the 4962 - is the hard drive parked? how do you cable the drive to the controller card, which is the correct controller card? Does the unit boot without a boot disk in the drive and look to the hard drive (like a PC) for the OS? What are drives called. I may have a BASIC disk somewhere intended for this computer, hmmm....

I do know what this system was used for originally. A medical records database system. The system used a modem to transmit info. It could have run a small computer department, there are a lot of serial cables. It would be fun to turn this into something else, after I have explored and documented how it was originally used.

See thread on


  Cabling 4956 to a 4962 Mod 4 drive unit by Bill Degnan - 05/30/2008 21:55
Cabling 4956 to a 4962 Mod 4 drive unit

There are 5 ribbon cables. Four for the hard drive and 1 for the disk drive.

I believe I have the correct cabling, based on the manuals.

I was not able to find any references to unparking the hard drive, so I will assume that this is not necessary.

I powered on the system with the 4978 display station.

Not much happened other than everything powering on and some lights.

I seek advice.

  Hi-res pictures by Bill Degnan - 04/18/2009 09:38
I have re-started this project with the help of Paul Shlichting out in California. He has Series 1 experience and offered to help walk through the restart process remotely. I took and posted some new hi-res pictures that we will use to verify that the cabling is correct and for removal of the hard drive parking plate(s).

New Hi-res photos



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