winscape 2309

As an example, the cold-start procedure on the Burroughs-Unisys V-series mainframes involved using the maintenance processor (in latter systems a convergent-Burroughs B25) to load a loader program from its floppy drive into the mainframe memory and invoke it. The little loader program had enough smarts to read from the various supported tape drives (7-9-18 track) and write to the various supported disk drives. The content of the tape was copied to the hard drive sans any manipulation of bits and then the system was halt-loaded from the operating system image on the disk. Any per-site OS configuration was done at halt-load time via a configuration file either provided by the maintenance processor to the OS or read from an 80-column card reader (this was the early 80's).

The older systems (pre 8" floppy) had a hardwired instruction sequence that would be executed on power-on which read the first 80-column card from the card reader, load its content into memory as the first-stage boot loader, and invoke it. The first card had enough code (represented as BCD digits) to read the rest of the boot loader from subsequent cards and the site configuration cards followed the boot loader.

The coldstart deck would start the tape to disk copy, the warmstart and halt-load decks would use the OS installed on the disk.

scott