Newsgroups: comp.sys.transputer
From: frank@bnkl01astro.ucla.edu (Frank Henriquez)
Subject: Adding Serial ports to a T800
Organization: UCLA Astronomy Dept.
Date: 8 Sep 1994 23:09:45 GMT
Message-ID: <frank-0809941609450001@kosh.astro.ucla.edu>

Hello:
  I'm trying to add a couple of serial ports to an existing in-house
design, based on a T800. I'd like to use a single chip dual port DUART,
like the MC68861 (or the equivalent Signetics part - SCN2681) or the
Z8530, but the bus transaction times for these devices is horrible; I
would have to add many wait states to the T800 just to meet the access
times of these devices.
 
   The baud rates required are pretty slow, typically 300 baud and never
faster than 9600 baud, so I could just add an RS-232 level shifter and a
latch and implement a software UART, but that would take some time to
develop.
 
My questions:
  1) Are there DUART chips that are fast enough to handle the transputer
bus speeds without all the extra wait state circuitry? any examples?
  2) is there any sample Occam code for a softweare UART?


Many thanks

Frank

-- 
   George Ogden Abell
Founder, UCLA Dead Astronomers Society
 
"I'm dead. Really"

