On 12/04/2015 09:04 AM, Paul Gilmartin wrote: > On Fri, 4 Dec 2015 08:00:52 +0000, Vernooij, CP (ITOPT1) - KLM wrote: > >> That's what NASA asked their programmers when designing the Apollo's. >> They answered: 'Nothing.'. >> 'Really, we can hardly believe this.'. >> 'It is true, we only use the holes in the punchcards.' >> > Decades ago, I was assigned to assist a scientist's converting his operation > to a central computer. One of the first questions he asked me was, > "How long can the computer remember a number?" > > -- gil > > ... > Maybe not what the scientist meant, but actually not an unreasonable question. It depends on where the number in stored. If you never bother to write it to external storage and just keep in in volatile memory, then it is only kept until some program deletes it or overwrites it or a power-down occurs. If you write it to external storage, it depends on the associated retention period of the data set containing it. It could be set for indefinite retention, or in other cases set for auto-deletion based on an event, elapsed time, or time since last referenced.
With older mainframes, some external media, and some PC platforms, mean-time-between-failure was significant as well. I do wonder if Einstein's relation between mass and energy means that theoretically a computer might have some minuscule difference in mass depending on the energy states of its internal components, If so, obviously not enough difference to be significant in the real world, but that could mean that in theory a computer might have a very slight variance in mass depending on what software was executing. -- Joel C. Ewing, Bentonville, AR jcew...@acm.org ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
