360/50 microcode listing

Mike Ross tmfdmike at gmail.com
Thu May 7 12:33:27 CDT 2015

1. IBM would very often lease rather than sell, and take back machines when
customers upgraded; it was obviously in their interests to control or
eliminate where possible the market in used machines.

2. Gold. A lot of gold in old IBM kit. I knew a scrap dealer in Chelmsford
UK that did nothing but break old IBM mainframes (only ever big boring grey
boxes when I was there in mid to late 1990s though!)

On 7 May 2015 13:16, "Jon Elson" <elson at pico-systems.com> wrote:

> On 03/13/2015 01:32 PM, Al Kossow wrote:
>> CHM was able to obtain volumes 18-20 of the IBM 2050 drawings, which are
>> the microcode charts and ROS dump. I got them scanned and uploaded
>> yesterday
>> to http://bitsavers.org/pdf/ibm/360/fe/2050
>> This was one of the things that I had been trying to locate for a while
>> now.
>>  Just a curious thing I've noticed.  Given the historic significance, and
> the large number of machines produced, I'm kind of amazed at the incredibly
> small number of 360's that apparently exist.
> Yes, I know, any would-be collector could drag home a PDP-8 and put it in
> his garage, even a whole rack mount system with an RK02 (or 3), dectape and
> paper tape reader, and still get his car in the garage.  And, the system
> could be run off normal mains power.
> You can't do that with a real 360 (some 360/20's were pretty small), even
> a 360/30 was a pretty big box.  And, you can't run a 360 off normal
> residential power, either.  Many of the peripherals used 3-phase motors,
> and hacking the converter/inverter to run off single phase would not be a
> task for any but the most experienced EE.
> But, it sure is a shame that there appear to be a tiny number of machines
> in existence.  One list shows 15 or 16 machines, excluding the model 20.
> Probably there are a couple more hidden somewhere, like the B1900 that came
> to light so recently.
> As fas as I can tell, NONE of these systems is complete enough to ever
> run, with the possible exception of the 360/30 at the CHM, which does seem
> to have a complement of peripherals, and maybe control units, too.
> Given the number of DEC 10's that are actually up and running, this seems
> a bit of a surprise.  there might be some emotional attachments that are
> behind this disparity.
> Anybody have some comments?
> Jon

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