[TUHS] What's with the DZ-11?

Noel Chiappa jnc at mercury.lcs.mit.edu
Thu Nov 27 07:41:39 AEST 2014

    > From: Dave Horsfall <dave at horsfall.org>

    > what was the problem with them?

Well, not a _problem_, really, but.... 'one interrupt per output character'
(and no way around that, really). So, quite a bit of overhead when you're
running a bunch of DZ lines, at high speeds (e.g. 9600 baud).

I dunno, maybe there was some hackery one could pull (e.g. only enabling
interrupts on _one_ line which was doing output, and on a TX interrupt,
checking all the other lines to see if any were i) ready to take another
character, and ii) had a character waiting to go), but still, it's still going
to be more CPU overhead than DMA (which is what the DH used).


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