26 Mar
2016
26 Mar
'16
9:09 a.m.
On Fri, Mar 25, 2016 at 7:10 PM, John Cowan <cowan(a)mercury.ccil.org> wrote:
So they did, but DEC machines in general were always ASCII. The PDP-8
used both 8-bit characters (ASCII with the high bit set) and 6-bit
ones (stripped ASCII without control characters or lower-case ones).
The former were packed three 8-bit characters in two 12-bit words; the
latter, two characters in one 12-bit word. The PDP-10 packed five 7-bit
characters into a 36-bit word with one bit left over, which was used
(if at all) for various purposes. Not until the PDP-11 did the 8-bit
character get aligned with the machine word size.
And Dec's RADIX-50, packing 3 characters into 16 bits. (IIRC the origin of
the 6.3 filenames. bit I can't document that.)
-- Charles