Could we agree to disagree and come together on improvements andclean-up?
paul at leyland.vispa.com
Mon Jun 2 11:43:11 CEST 2008
On Mon, 2008-06-02 at 10:00, Vincent Lefevre wrote:
> > > No, long should just fit the needs. What if a processor has 32-bit
> > > words and use pointers on 64 bits (two words)?
> > Would you expect to see such CPU?
> Strangest CPUs have been seen in the past. And some CPUs such as DSPs
> have particular features.
Indeed. Programming early IBM-PC machines was, er, "interesting" with
their different memory models. My first paid employment as a programmer
was porting PDP-8 (a 12-bit word, 8-bit byte machine) Focal to Z80 (a
machine with 8-bit words and 16-bit (2 words) pointers) BCPL. My first
real programming was done on an ICL 1906a, which was a 24-bit 8-bit byte
machine. My first full-time job was microcoding a machine that was
intrinsically a 32-bit word address architecture but which had bits 26
and 27 (I think, this is almost 30 years ago, so I may have an
off-by-one error in my memory) to support 8-bit byte addressing.
More recently, I've programmed heterogeneous clusters where you most
certainly can not assume that all the cpus have the same architecture or
even word length. That particular work was done with Condor on sundry
Sun boxes both M68K and Sparc. A current example of a heterogeneous
cluster on a chip is the PS3, so such things are still relevant.
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