Mystery IBM processor

Mike Ross tmfdmike at
Sat May 28 08:03:40 CDT 2016

On Sat, May 28, 2016 at 11:40 PM, Dave Wade <dave.g4ugm at> wrote:
>> -----Original Message-----
>> From: cctech [mailto:cctech-bounces at] On Behalf Of Mike Ross
>> Sent: 28 May 2016 11:29
>> To: General Discussion: On-Topic Posts <cctech at>
>> Subject: Re: Mystery IBM processor
>> On May 28, 2016 9:51 PM, <malcolm at> wrote:
>> >
>> > Just wondering if anyone can help us to identify a rather large IBM
>> > processor assembly. It weighs around 60 pounds.
>> >
>> > The frame has a P/N of 34F5089. The frame houses 9 modules, 6 of which
>> > are installed. The module we removed for inspection has a P/N of 34F0615.
>> Definitely IBM mainframe. The individual square alloy lumps are what are
>> called MCMs - Multi Chip Modules. Insides are dozens of individual ECL ICs.
>> Water cooling heatsinks would have been bolted to the front side in life.
>> Can't remember what IBM called the entire assembly. 1980s, probably a 3080
>> or 3090 but don't quote me on that.
> I believe the modules are called TCM's or Thermal Conduction Modules. It looks like a 3090 chip but I thought those were withdrawn before the date code of "90xx".
> I thought the ES/9000 follow on had a re-designed chip with multiple rows of pins like this...
> but when I look at the IBM web pages:-
> it says only the high end machines have the new TCM so I think it may be a TCM from an entry level ES/9000 machine...

TCM! That's what I was looking for. If you think your collection is
getting out of hand Jim Austin has *half* of a 3084.... shows how the
CPU assembly fits into the machine:

'No greater love hath a man than he lay down his life for his brother.
Not for millions, not for glory, not for fame.
For one person, in the dark, where no one will ever know or see.'

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