On Fri, 2007-12-07 at 12:59 -0500, James Knott wrote: > Aaron Kulkis wrote: > > James Knott wrote: > >> Back in the days when I supported mini-computers, everything was TTL > >> logic, with ECL used in some critical areas. The CPU was two 15 inch > >> square boards! A 200 MB disk pack drive was the size of a washing
I wrote a driver for a washing machine-sized disk, but it was only 8 MB. The older machines we used had 6' tall drums for backing store. > >> machine and required 3 phase power. Some of the systems I worked on > >> were water cooled. Back in those days, I worked down to the microcode > >> level, that is the instruction set within the CPU, that enabled it to > >> run the instruction set the applications would use. > > > > And some CPUs from IBM even had the capability of CHANGING > > instruction sets between processes. Like an IBM 370 could > > simulate several single-user IBM 360's and single-user IBM > > 704's by just switching microcode with each context switch. Yes the driver was for a machine called VCS - variable microcode system. It had COBOL microcode, FORTRAN microcode etc. It was a development of Iliffe's basic language machine. It had a variable pot to set the clock speed. Early in the morning it was cranky and had to be booted at low speed and then you wound the clock up as it warmed up. Cheers, Dave -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
