Computers as big as houses... back to the 60's

Instruction pre-fetching
This term was used by IBM and referred to the IBM/360, which saved time by anticipating the most likely next course of action - if the machine "guessed" incorrectly, nothing was lost; but if right, a few nanoseconds were gained. I gather the current term term is 'speculative execution', which appears to carry some risk, in that discarded lines of action can end up in cached memory - which can later be interrogated by malware.

Graceful degradation
This was an ICL 4-70 concept. For a long time the manual said "Graceful degradation is not yet implemented." When it finally came, it enabled the machine to do a few useful things if the mains supply was suddenly cut - during the dying cycles of power the central processing unit managed to store some vital checkpoints in assorted registers. Hopefully when the power came back on, you could pick up where you left off.

I have always tried to fashion my life according to these two simple concepts, that of using idle time to prepare for the statistically-most-likely outcome - until proved otherwise - and the art of maintaining elegance of operation, even under pressure so great that it provokes a temporary collapse.

...return to commonplace book index