OK, forgive me if I'm a little fuzzy here. I believe that IPL was Initial Program Load and BZUP was Block Zero Utility Program. We had to get that 400 octal block of data into memory to start up the operating system. We would use the front panel toggle switches set to 376 and press a momentary "Examine" toggle. Then we would set the switches to 601xx and press the momentary "Deposit" toggle. This was a "No Input Output Start" command to device number xx. This was the device number of a mag tape, hard disk, paper tape, or other controller. Then we would set the switches to 377 and press the momentary "Deposit Next" toggle. This was just a jump back one instruction. We would then set the switches back to 376 and press the momentary "Run" toggle. This caused a transfer of the first block of operating system data into memory until the little toggle routine loop got overwritten by the program. The data then written into 376 and 377 would probably be considered a cold start vector. It would point to a much more elaborite program, just loaded into Block 0, to load more of the operating system.
Joe
[This message has been edited by JoeTestingEngr (edited 10-08-2006).]
