15 Feb
2025
15 Feb
'25
3:19 p.m.
On 2/15/25 12:34, Wayne S via cctalk wrote:
6 bit characters were used by CDC 24 bit machines. 4
chars per 24 bit word.
There were *many* six-bit codes, even differing among systems offered by
the same vendor. exempli gratia: IBM 1401/1620/7090 CDC
1604/3000/6000; all different between the various machines. CDC 6000
Display code is an interesting one; as the 00 code could either be an
end-of-record/line or a colon, depending on the placement in a 60 bit
word. CDC also supported 6 bit ASCII subset on some of their systems.
I recall a proposal in the 70s being circulated around CDC CPD as to
what should be done to extend the nominally 63/64 character set to 8
bits. The scheme that was eventually adopted repurposed some codes as
"escape" or prefix codes. But there were proposals for 10 bit
characters (6 per word) and one that I was particularly fond of: 7.5
characters per word, each word being called a "snaque" (get it?
bit/byte/snaque...)
Univac used Fieldata well into the 80s, ISTR.
--Chuck