Re: What is byte-code ?

glen herrmannsfeldt <gah@ugcs.caltech.edu>
16 Apr 2005 11:14:45 -0400

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[16 earlier articles]
Re: What is byte-code ? kers@hpl.hp.com (Chris Dollin) (2005-03-31)
Re: What is byte-code ? nathan.moore@sdc.cox.net (Nathan Moore) (2005-04-02)
Re: What is byte-code ? slimick@venango.upb.pitt.edu (John Slimick) (2005-04-11)
Re: What is byte-code ? kers@hpl.hp.com (Chris Dollin) (2005-04-11)
Re: What is byte-code ? anton@mips.complang.tuwien.ac.at (2005-04-11)
Re: What is byte-code ? nathan.moore@cox.net (Nathan Moore) (2005-04-16)
Re: What is byte-code ? gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-04-16)
Re: What is byte-code ? ralph@inputplus.co.uk (2005-05-09)
Re: What is byte-code ? gah@ugcs.caltech.edu (glen herrmannsfeldt) (2005-05-13)
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From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.compilers
Date: 16 Apr 2005 11:14:45 -0400
Organization: Compilers Central
References: 05-03-015 05-03-026 05-04-022
Keywords: architecture
Posted-Date: 16 Apr 2005 11:14:45 EDT

John Slimick wrote:




> I've been following this thread and I find that there are assumptions
> about "byte." In my career bythes were six bits until April 1964 when
> they became 8 bits (IBM 360).


In the pre-360 books that I have seen the six bit unit seems to be
called BCD. That is, the code before EBCDIC was called BCDIC, but it
seems that IBM called them BCD, even though it would seem the term
should be used for numeric data.


The IBM Fortran manual calls them "storage locations", I remember
being confused why everyone was calling them bytes, when the book
didn't have that word anywhere in it.


> Now with the advent of UNICODE it seems that bytes are becoming 16
> bits, at least conceptually. (And then there were the 5 bit Baudot
> "bytes"). I think everyone is talking about "octets," so why can't
> we use them?


It seems that in C, and the PDP-10 bytes can have a variety of sizes,
but to some people and some machines they are always eight bits.


>>My point here was to do something that would compile correctly on any
>>machine and work effeciently/quick without having to be configured
>>slecial for that machine. Other areas have to worry about endianness
>>and other protability issues, but the more areas that you can make them
>>non-issues, the better.


In the Fortran 66 days the only portable way to do anything with
character data was with one character per Fortran storage unit (the
size of an INTEGER or REAL variable). That is, A1 format. Word
addressed machines were popular enough that you couldn't do much else.


> [Probably because the bytes in byte code don't have to be 8 bits. either.
> -John]


In that case, what are the bytes in byte code?


I suppose I don't like the name that much anyway, so I can't
really disagree with the meaning.


-- glen


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