7 Jan
2019
7 Jan
'19
6:45 a.m.
On Jan 7, 2019, at 12:24 AM, Dave Wade via cctalk
<cctalk at classiccmp.org> wrote:
...
I am also pretty sure that prior to S/360 the term "character" was generally
used for non 8-bit character machines. I am not familiar with the IBM 70xx series machines
but certainly on the 1401 and 1620 the term byte was never used.
The 1620 is a decimal machine, with digit-addressed memory. It has a number of
instructions that operate on digit pairs, for I/O, so those pairs are called
"characters".
Also the Honeywell H3200 which was an IBM1401
"clone" (sort of). The only machine I know where a "byte" is not eight
bits is the Honeywell L6000 and its siblings These machines had 36 bit works which were
originally divided into 6 six bit characters.
Others have already pointed out there are plenty of other examples, with other
definitions. I mentioned the CDC 6000 series mainframes.
Just to make sure of my memory, I searched some documentation. Here is a quote from the
CDC Cyber 170 series Hardware Reference Manual (section "Input/output multiplexor -
Model 176"):
"During communications between the PPUs and CM, the I/O MUX disassembles 60-bit
transmissions from CM to 12-bit bytes."
But here's one I had not seen before: in the 7600 Preliminary System Description, the
section that describes the PPU I/O machinery has the same sort of wording as above, but
then on the next page the discussion of the drum memory says:
"A 16 bit cyclic parity byte is generated by the controller for the data field of
each record written on the peripheral unit."
And the CDC 6000 series Sort-Merge utility has a "BYTESIZE" control card, which
in PDP-10 fashion allows "byte" to be any length up to 60 bits (the word size)
-- the default is 6 bits, which is character length for the basic character set but other
examples show 12 and 60 bit "bytes". In the same way, a TUTOR language manual
from 1978 describes bytes as being any size, in a description of the language feature for
what C calls bit-field variables. I didn't realize that term was used for that
feature, though.
paul