character codes and punched cards (was Re: y2k stuff)

From: Eric Smith <eric_at_brouhaha.com>
Date: Tue Jan 12 17:01:47 1999

I wrote:
> For instance, the IBM 1401, which typically was booted from cards, but
> had only 64 distinct characters.

Hans replied:
> Shure ? the 1401 is a bit before my time, but didn't they
> already use 12 row cards with EBCDIC coding (like 12,1 to
> 12,9; 11,1 to 11,9 and 0,2 to 0,9 for A-i; J-R and S-Z) ?

The 1401 most definitely did not use EBCDIC. It only had six
bit characters, with a seventh bit to serve as a word mark,
and an eighth (non-programmer-accessible) parity bit. The
word mark was used to denote the (leftmost?) end of a field,
for variable-field-length instructions.

However, since EBCDIC was by design (and by name) an extended
version of existing codes, the 1401's card code is similar.

Eric
Received on Tue Jan 12 1999 - 17:01:47 GMT