[FoRK] Fucked by the French

Andy Armstrong andy
Mon Oct 3 15:20:17 PDT 2005


On 3 Oct 2005, at 22:34, Dr. Robert Harley wrote:
> 6502 is the first machine I was into but ARM was the one that grabbed
> my attention - after writing flood-fill routines for both circa 1988,
> the choice made itself. At the time and for a while thereafter, I had
> dreams which involved writing ARM code and counting cycles therein.

For my money ARM is still the cutest processor architecture - a  
legacy of a time when Acorn were absolutely at the top of their  
technical - if not sales - game. I managed to boot up an old Risc PC  
the other day and took the opportunity to grab a copy of all my old  
ARM assembler source from the hard drive. Then I spent a nostalgic  
couple of hours just browsing the source and amusing myself with the  
beauty of the programming idioms that followed naturally from the ARM  
architecture. Anyway, I sense I'm sharing too much... :)

Highlights for those who missed them first time round:

* All instructions one 32 bit word long, all memory access word aligned
* Sixteen more or less general purpose 32 bit registers one of which
   just happens to be the program counter
* Conditional execution on all instructions - not just jumps and  
branches

This last combined with the ability to choose on an instruction by  
instruction basis whether the flags are updated leads to some  
thrillingly compact and efficient code.

> PS: Was that clear enough? I'll repeat it if need be.

No, got it thanks :)

-- 
Andy Armstrong, hexten.net



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