360/50 microcode listing

Jon Elson elson at pico-systems.com
Fri May 8 10:23:00 CDT 2015

On 05/07/2015 10:20 PM, jwsmobile wrote:
> On 5/7/2015 6:57 PM, Jon Elson wrote:
>> Lots of 360's were owned in the later days.  All the ones 
>> I knew of, with the possible exception of Washington 
>> Universities' first 360/50
> The UMR 360/50 was one of the first owned 360s.  They were 
> given a 360/40 because IBM could not deliver the 50 on 
> schedule.  I don't know how that was handled.
> The 50 at UMR was also odd because it was a 512K main 
> memory machine, and 1mb of LCS, giving a non power of 2 
> memory size. Supposedly lead to some bug fixes.
Shouldn't have needed much software tinkering, as a number 
of other models could be set up with non power of 2 memory 
size.  Maybe a hardware quirk was that it needed to make a 
program exception if you addressed a 1.7 MB location, and 
instead it would get a machine check with a main store 
parity error.  That would take maybe just one added gate to 
trigger the program exception on the right combination of 
address bits.
> Ran HASP and MVT 21, as well as CPS
Well, I gotta say, our 360/65 sure beat the pants off the 
360/50 that it replaced.  In fact, the /65 beat the pants 
off TWO 370/145's they had.  They used the /145's for 
"timesharing" and got FOUR users per machine!  Wow, that was 
a riot.

Ahh, the "old days".


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