On Thu, 15 May 2008 20:27:31 -0500, William H. Blair <[EMAIL PROTECTED]> wrote:
>> >The System/360 Model 75 was not an UNcommon machine (as were >the Models 91, 95, 85 and 195) but it was not exactly common. >Only VERY large shops would feel the need for one. NASA had >five which were used to support the Apollo moon program. And >lots of universities had one or two. For businesses, a 360/40 >or 360/50 were "common." Big businesses might have a 360/65 >or two (instead of a 360/75, since it was almost as fast, but >much cheaper). <------------- Wonderful post snipped for brevity ------------------> Thank you for that, William. I was told that there were five model 75's in the UK, and I worked on three of them. Two were at IBM's Havant plant where they made 165's and 168's, the other one was CDC Data Services (formerly ITT Data Services) at Barnet. IBM also had a model 50 and CDC had a 65 running some time sharing software. The IBM machines ran MFT-II as did the CDC one when I joined, but we migrated to MVT so we could have TSO. Operating System MTBF at Barnet was less than 24 hours, I think the IBM machines were more reliable but then CDC was a Service Bureau and developers did strange things. CDC ran HASP-II but I think the IBM machines used readers and writers. One of them had an old tape drive converted to write on 8 inch floppy disks (a Dolphin drive after the Havant pub) which held the microcode on the 168s. One of the Havant 75's had to have all its logic cards replaced, we Ops were told it was because of alminium migration, but that may have been a CE windup. I left CDC in 1975 and it was only about a year before I was again using a one MIP machine when Monsanto replaced their 145 with a 158-3. This of course was TINY compared to the old 75s - how did they fit all that power into such a small box? We hadn't heard of Moore's Law then. TGIF Dave ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
