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More DZ Serial driver

Subject: More DZ Serial driver
From: Thomas Riemer <>
Date: Thu, 29 Oct 1998 23:40:57 -0500 (EST)
I've worked through all the details of getting characters to 
be received on the DZ serial driver...

I've also worked through the details of getting characters to 
transmit on the DZ serial driver line...

But I can't get them both working at the same time. 

Here's the problem that I'm running into:
1. register TZ_TCR has LNENB[3-0] - pins which when 
   high are supposed to enable the transmitter logic for the outgoing 
   lines.  Setting these seems to generate an infinite number
   of interrupts on empty buffer condition.  I would have expected
   a single interrupt - but it seems to generate them continuously.
   Everything in documentation indicates that there should be a single

2. register TZ_LPR has pin RXENAB that needs to be set in order to 
   receive characters. (as well as the line pins to indicate which line
   to receive on)  For some reason, the LNENB line from TCR need
   to be set in order to receive characters...
3. The problem I run into is that the continuous interrupts are kicking 
   in before the standalone shell ever gets a chance to do anything.
   The code was set up to turn off LNENB if there were no characters
   waiting to be queue - but in the process this seems to be violating
   the requirement #2. 

None of these hypotheses really make much sense standing alone - and
don't really explain what I'm seeing.  Having pounded my head hard on 
this for about 2 weeks - I'm in need of some suggestions on how
to approach the problem. 

-Tom Riemer
Given enough eyeballs all bugs seem shallow.

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