3 ms·
I happened to come across the Alto's time handling code [1] while looking for something else. The Alto counts seconds since Jan 1, 1901 and the time can run unt
by kens 10y ago
I happened to come across the Alto's time handling code [1] while looking for something else. The Alto counts seconds since Jan 1, 1901 and the time can run until 2036 since it uses a 32-bit value. (Unix time in comparison runs from 1970 to 2038; it runs half as long because it loses a bit by using a signed value.)
The point of this is the Alto can handle dates until 2036, but will run into problems two years before Unix self-destructs in 2038.
[1] http://xeroxalto.computerhistory.org/Indigo/AltoSource/TIMESOURCE.DM!2_/.TimeConvB.bcpl.html http://xeroxalto.computerhistory.org/Indigo/AltoSource/TIMES...
- userbinator 10y agoGood to see they at least thought some reasonable amount of time into the future; in contrast, the Apple Lisa, released 10 years after the Alto and a few years after the IBM PC, had an RTC that only went to 1995: https://systemfolder.files.wordpress.com/2009/11/lisaem-date.png https://systemfolder.files.wordpress.com/2009/11/lisaem-date... http://lisafaq.sunder.net/lisafaq-hw-io-cop421_clock.html http://lisafaq.sunder.net/lisafaq-hw-io-cop421_clock.html (Apart from this shortsightedness, the rest of the Lisa's design is also... interesting. Proprietary custom ICs, a pretty much locked-down user-is-an-idiot GUI, and complete separation between users and developers. It failed then, but unfortunately the same strategy is now considered the norm 30 years later...)
- fanf2 10y ago32 bit unsigned seconds spanning 1901-2036 is the same representation as NTP.