🚀 go-pugleaf

In article <1990Jan4.1...@gdt.bath.ac.uk> exs...@gdr.bath.ac.uk (P E Smee) writes:

>OS/8 (on DEC PDP-8's) had generously allocated an entire 3 (THREE,
>count 'em, 3)bits for the year field in filesystem dates.  (In minor
>defense, they only had 12-bit words, and needed 9 bits to hold
>day-of-year.  Still, sounds like they didn't expect the OS to be
>popular or long-lived.)
>
>Originally, the 'base' year was 1960.  Late in 1967, someone finally
>realized that something would have to be done about this.  The approach
>they took was to use a sliding base year.  So, in encoding an ASCII
>date into a filesystem date, the algorithm was (YEAR-1960) mod 8.  In
>turning a filesystem date back to an ASCII date, it would pick the most
>recent past year which would have given the encoding.  So, in 1968,
>everything that had been lying around unchanged since 1960 suddenly
>looked brand new.

Not entrirely correct. Here is the story so far (it ain't over yet):

First of all, the base year was 1970, so the time was running out
at the end of 1977. What DEC decided to do, was to extend the date
with two more bits in a totally different place in the memory,
so the OS/8 date is now valid to 2001, though it is officially
valid until 1999, since everybody knows what will happen when
the hundreds change.
The problem is files. Since they only had 12 bits allocated,
and no extra space available to store the two new bits,
filedates became relative. So, files older than 8 years, do
show up wrong in the directory. OS/8 itself has the date
right though.

>If I recall correctly, they did NOT take the current day-of-year into
>account when converting the year code back to readable form, so that
>you could also find files which appeared to have been (have will been?)
>created in the future -- that is, at a later date in the current year.

Nope. This is wrong. The programs, such as DIRECT, checked if the
date becomes the future, and in that case, substracts eight
years from the date, when printing. Remember, OS/8 knows
the correct date!


While I'm at it, I'll throw another OS/8 secret message in.

OS/8, like most other operating systems, has a SET command,
which can modify the behaviour of different devices.
Well, OS/8 SET was obviously inspired by the TOPS-10 SET
in one aspect. There is a SET option for the TTY called
GAG. On TOPS-10 (and other multiuser systems) it is
used to disable messages to pass through.
Well, on OS/8, that was obviously meaningless, but the
option was still included, and the word "GAG"s other meaning
was used, so if you typed ".SET TTY GAG" OS/8
responded:

A FUNNY THING HAPPENED TO ME ON THE WAY TO THE COMPUTER ROOM.
A PANHANDLER CAME UP TO ME AND SAID,
"CAN YOU SPARE ME $25,000 FOR A CUP OF COFFEE?"
"WHY SO MUCH?", I ASKED IN AMAZEMENT.
"THINGS HAVE BECOME SO AUTOMATED", HE REPLIED,
"THAT THE ONLY WAY I CAN ORDER IT
IS WITH A COMPUTER ORDER FORM".

This is, as far as I know, totally undocumented.

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Everybody know that the DECstation is a pdp8, which is a RISC,
but where did MIPS computers get into it?

	- Johnny Billquist
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