henry@utzoo.UUCP (Henry Spencer) (12/18/86)
> A word is the 'natural' unit of operations on a machine. > (Which means that 32 bits on a vax should really be called a word, not > a longword.) The only reason it's called a longword is because of all the semi-subliminal it's-really-just-a-big-pdp11-so-don't-worry-about-incompatibility marketing horseshit that surrounded the vax in its early days. Remember when a 780's official designation was a "VAX-11/780"? (Well, to be honest, there may be another reason: it may be a historical survival from the early vax development days, at which time I suspect the vax was going to be much more of a stretched 11 than a new machine. Note that "VAX" stands for Virtual Address Extended. Extended what? Extended pdp11.) -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,decvax,pyramid}!utzoo!henry
campbell@sauron.UUCP (Mark Campbell) (12/19/86)
In article <7426@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: >> A word is the 'natural' unit of operations on a machine. >> (Which means that 32 bits on a vax should really be called a word, not >> a longword.) > >The only reason it's called a longword is because of all the semi-subliminal >it's-really-just-a-big-pdp11-so-don't-worry-about-incompatibility marketing >horseshit that surrounded the vax in its early days. Remember when a 780's >official designation was a "VAX-11/780"? >-- > Henry Spencer @ U of Toronto Zoology > {allegra,ihnp4,decvax,pyramid}!utzoo!henry [For what it's worth...] A DEC field representitive in the late 70's told me that the reason that the VAX word was 16 bits was that the Government classified machines by word size when purchasing -- thus the VAX would have competed with a higher class of machines in contracts. -- Mark Campbell {}!ncsu!ncrcae!sauron!campbell
spain@alliant.UUCP (Dave Spain) (12/22/86)
In article <7426@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: >Remember when a 780's official designation was a "VAX-11/780"? I'm not sure this ever changed. There (believe it or not) is a good deal of logic behind this designation and I don't just mean in the philosophical sense. All VAX processors that I was familar with that used the "-11/" nmemonic offered some form of hardware assisted compatibility-mode, typically at the instruction set level. It wasn't until after a descision was made to offer PDP-11 compatibility as a software option was the "-11/" convention dropped.