there is hope for tiny code!

Sean 'Captain Napalm' Conner spc at conman.org
Sat Apr 15 21:46:37 CDT 2006


It was thus said that the Great Roger Merchberger once stated:
> 
> Rumor has it that Richard may have mentioned these words:
> >OK, in some threads I've seen the curmudgeons shake their head back
> >and forth and bemoan how people don't write finely tuned hand assembly
> >code anymore.
> 
> Drivewire for the Tandy CoCo1/2/3 (http://www.cloud9tech.com.) use 
> hand-tuned assembly for the serial routines on the bit-banger (one bit of a 
> PIA, toggled by software) port - they acheive 38400bps on a .89Mhz 6809 
> (CoCo1/2), and 57600 on a 1.78Mhz 6809 (CoCo3). I've booted NitrOS9 on my 
> machine, and it's pretty durned quick. Not *quite* as fast as the floppy 
> drive (and certainly not as fast as the CF memory card I have on the IDE 
> bus ;-) but awfully handy! (Oh, and check out the SuperBoard project...)

  Really?  I did the math once and found that 19200 was about the
theoretical maximum one could get on a Coco 1/2---but I suppose if you
unrolled the loop to read a byte you could, maybe, get a bit faster at the
expense of space ... hmm ... as I'm doing it, yes, I think it is possible by
unrolling the loops, but the timing is *very* tight.

  -spc (And certainly not usable for generalized 38400 speed communications
	it seems like ... )






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