Jack Coats wrote: > In the old days I worked on IBM mainframes, and a small mainframe (4341 if I > remember right) had a generator > set to help isolate the power. A crazy friend of mine bought a pair of 370-145 "mainframes" that were retired at our work. We tore one apart for parts, and actually tried to get the other one working. They had a 17 KVA motor generator set in the back, that converted 208 3 phase 60 Hz power to 115 V 3 phase 415 Hz power. I guess that means a 2-pole induction motor turning a 14-pole alternator at about 3560 RPM. Unfortunately, his small house had only a 60 A 240 V service, and we were never able to get the motor up to delta connection without tripping his main breaker.
So, important digital loads on the machine ran off the MG set, but the cooling fans, floppy drive motor and front panel lights ran off the 60 Hz power. The power supplies were quite small for linear supplies. They had 3-phase transformer-rectifiers, and then a thing they called an electronic capacitor. During the line peaks they shunted current through a big inductor, then turned this off during the dips between cycles. This allowed them to use a TINY capacitor for a pretty hefty supply, like 5 V at 300 A. The 370/145 was an insanely primitive minicomputer running an amazingly "vertical" microcode emulation of the 370 instruction set, and the performance showed it. They ran VM/370 and a bunch of MVS and TSO systems under it. It generally took them 45 minutes to an hour to bring all these OSes back up after a crash. TOTAL insanity. Jon ------------------------------------------------------------------------------ Increase Visibility of Your 3D Game App & Earn a Chance To Win $500! Tap into the largest installed PC base & get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
