off topic - capatob - saratov2 computer Russsian pdp8

[Noel Chiappa]

    > From: Dave Wade

    > The only machine I know where a "byte" is not eight bits is the
    > Honeywell L6000 and its siblings

I'm not sure why I bother to post to this list, since apparently people don't
bother to read my messages.

>From the "pdp10 reference handbook", 1970, section 2.3, "Byte Manipulation",
page 2-15:

"This set of five instructions allows the programmer to pack or unpack bytes
of any length from anywhere within a word. ... The byte manipulation
instructions have the standard memory reference format, but the effective
address E is used to retrieve a pointer, which is used in turn to locate
the byte ... The pointer has the format

 0   5 6   11 12 13 14   17 18   35
   P     S       I     X       Y

where S is the size of the byte as a number of bits, and P as its position
as the number of bits remaining at the right of the byte in the word ... To
facilitate processing a series of bytes, several of the byte instructions
increment the pointer, ie modify it so that it points to the next byte
position in a set of memory locations. Bytes are processed from left to
right in a word, so incrementing merely replaces the current value of P
by P-S, unless there is insufficient space in the present location [i.e.
'word' - JNC] for another byte of the specified size (P-S < 0). In this
case Y is increased by one to point at the next consecutive location, and
P is set to 36 - S to point to the first byte at the left in the new
location."

Now imagine implementing all that in FLIP CHIPs which held transistors
(this is before ICs)!

Anyway, like I said, at least ITS (of the PDP-10 OS's) used this to store
ASCII in words which contain five 7-bit _bytes_. I don't know if TENEX did.


    > I also feel the use of the term Octet was more marketing to distance
    > ones machines from IBM.....

Huh? Which machine used the term 'octet'?

Like I said, we adapted and used the term 'octet' in TCP/IP documentation
(and that's definite - go check out historical documents, e.g. RFC-675 from
1974) because 'byte' was at the time ambiguous - the majority of machines on
the ARPANET at that point were PDP-10's (see above).

Interestingly, I see it's not defined in that document (or in the earlier
RFC-635), so it must have already been in use for an 8-bit quantity?

Doing a little research, there is a claim that Bob Bemer independently
invented the term in 1965/66. Perhaps someone subconciously remembered his
proposal, and that's the ultimate source? The term is also long used in
chemistry and music, of course, so perhaps that's where it came from.

	Noel