3 ms·

Was there a more convenient way to perform the bootstrap? Couldn't it have been in some kind of ROM? It appears to be only a handful of bytes.

inyorgroove 6y ago
I also wondered this, what did the pipeline company do if/when there was a loss of power?
- rst 6y ago
  What you saw was the cold start procedure for a completely uninitialized machine -- manually enter a short bootstrap loader of a dozen instructions or so, just enough to load a longer one from whatever I/O device was handy. A lot of machines had this kind of start procedure -- if there's a large row of switches on the front panel, that's probably what they were there for. (Core memory would retain its contents without power, so if you were absolutely sure nothing could possibly have disturbed that initial bootstrap routine since the last time you toggled it in, it might still be there. But a lab minicomputer of that era, probably didn't have any memory protection at all, so that's a pretty big "if".)
  - bananicorn 6y ago
    Why is this being downvoted? Is it incorrect?
    - implements 6y ago
      I saw a Prime 750 minicomputer cold booted exactly as described in the 1980s - so I can’t see any problem with that post. Edit: It’s describing a situation where a “Resident Monitor” isn’t built in, but is manually loaded after power up. https://en.m.wikipedia.org/wiki/Resident_monitor https://en.m.wikipedia.org/wiki/Resident_monitor
phire 6y ago
These early mini computers were cost optimised. Their earlier mainframe cousins often had features to easy "Initial Program Loading". The IBM 1401 had a load button that was hardwired to read a single punchcard (80 6bit words) into memory locations 001 to 080 and jump to it. The CDC6000 had a panel with 144 toggle switches, acting essentially as a 144 bit bootrom. (12, 12bit words) These were expensive mainframe computers, so they could usually afford some budget towards IPL functionality. But I guess even these cheaper minicomputers were expected to stay on long enough that there was little point spending money on IPL functionality to make cold booting easier.

inyorgroove 6y ago

I also wondered this, what did the pipeline company do if/when there was a loss of power?

rst 6y ago
What you saw was the cold start procedure for a completely uninitialized machine -- manually enter a short bootstrap loader of a dozen instructions or so, just enough to load a longer one from whatever I/O device was handy. A lot of machines had this kind of start procedure -- if there's a large row of switches on the front panel, that's probably what they were there for. (Core memory would retain its contents without power, so if you were absolutely sure nothing could possibly have disturbed that initial bootstrap routine since the last time you toggled it in, it might still be there. But a lab minicomputer of that era, probably didn't have any memory protection at all, so that's a pretty big "if".)
- bananicorn 6y ago
  Why is this being downvoted? Is it incorrect?
  - implements 6y ago
    I saw a Prime 750 minicomputer cold booted exactly as described in the 1980s - so I can’t see any problem with that post. Edit: It’s describing a situation where a “Resident Monitor” isn’t built in, but is manually loaded after power up. https://en.m.wikipedia.org/wiki/Resident_monitor https://en.m.wikipedia.org/wiki/Resident_monitor

phire 6y ago

These early mini computers were cost optimised. Their earlier mainframe cousins often had features to easy "Initial Program Loading". The IBM 1401 had a load button that was hardwired to read a single punchcard (80 6bit words) into memory locations 001 to 080 and jump to it. The CDC6000 had a panel with 144 toggle switches, acting essentially as a 144 bit bootrom. (12, 12bit words) These were expensive mainframe computers, so they could usually afford some budget towards IPL functionality. But I guess even these cheaper minicomputers were expected to stay on long enough that there was little point spending money on IPL functionality to make cold booting easier.