Byte sizes (was Re: 2.8M 3.5' floppy

Paul Koning pkoning at equallogic.com
Tue Mar 15 09:22:44 CST 2005


>>>>> "der" == der Mouse <mouse at rodents.montreal.qc.ca> writes:

 der> This must be a different California from the one that developed
 der> 4.3BSD for the VAX, a machine on which a byte is 8 bits, a word
 der> 16, and 32 is a long (or more formally longword) - terminology
 der> inherited in large part (in toto?) from the PDP-11 and for some
 der> reason I do not understand not updated to match the VAX.

"word" for 16 bits and "longword" for 32 bits IS the VAX terminology.
The VAX kept the PDP-11 terminology for the simple reason that the VAX
was supposed to be seen as an upward compatible extension of the
PDP-11.  That's clear from the PDP-11 instruction set emulation, of
course.  It's also clear from the data formats used -- not just the
integer data but also F and D float come straight from the PDP-11,
even though on a VAX those layouts look very contorted.

     paul



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