On Thu, Oct 28, 2010 at 9:04 PM, Dave Close <[email protected]> wrote: > Brandon S Allbery KF8NH wrote: > >>I'll add that "octet" is itself something of a leftover from when the 36-bit >>dinosaurs walked the earth.
Hi! My name is Tom, and I'll be your dinosaur for the evening. > That doesn't seem right to me. Certainly 36-bit machines (and 12-bit and > 18-bit ones) frequently divided instruction words into 3-bit units and > used octal notation to represent them. But 36%8 != 0. 36-bit machines used several character sets. Most 36-bit machines (IBM, Honeywell, DEC) started with 6-bit character sets. BCD, SIXBIT, etc. Note that EBCDIC is the *Extended* Binary Coded Decimal Interchange Code, eg it was an 8-bit extension of the earlier 6-bit character set. When EBCDIC and ASCII came along, some hardware offered multiple ways to pack 8-bit characters into 36 bits. Honeywell/GE Multics and GCOS (36-bit) hardware offered either 4x8-bit characters all packed into the lowest bits plus padding bits at the top of the 36-bit word -or- 4x 9-bit bytes with the most significant bit of each byte as padding. And there were *hardware* instructions to process all these formats, and to convert to/from each format and between character sets, even. --tep, the dinosaur _______________________________________________ Tech mailing list [email protected] http://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
