On Sun, Mar 10, 2002 at 01:02:45PM +1030, Greg Lehey wrote:
: >> [...], but later they moved to 9 bit ASCII.
: > ...isn't ASCII 7 bit by definition?  Or is "9 bit ASCII" an
: > abbreviation for "ASCII in the low 7 bits of a 9-bit field"?
: Yes.  
: > (And in that case, I'm curious: what did the other 3/4 of the
: > possible values mean, do you happen to know?)

When I used it, the UNIVAC 1100/nn thingy used bytes of 6, 9, 12, and
18 bits, or 6, 4, 3, 2 bytes per word.  There was a status bit which
said whether it would do 12/3 or something else (I think it was 9/4)
for the same instruction bits.  Byte accesses were typically done with
an array of instructions set up to handle successive bits, and you
executed one of the instructions in the array, using an appropriate
execute indirect instruction, whose name I have forgotten.

9-bit ASCII just meant the smallest byte size big enough to hold a
7-bit ASCII value.  I don't remember playing with undefined bits.

Integers were 1-s complement, and I think floating point was
sign-magnitude.  Text lines were stored as word count followed by
content, so you frequently had trailing whitespace, even on a
minimum-length line.

Ah, nostalgia.  Then I moved on to the PDP10...

-- 
Christopher Vance