360/50 microcode listing

Jon Elson elson at pico-systems.com
Thu May 7 12:16:33 CDT 2015

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?


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