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Newsgroups: comp.sys.nsc.32k
Subject: Re:  PC532 Expansion & other questions
Message-ID: <9011300212.AA05577@virtech.UUCP>
Date: 30 Nov 90 02:12:45 GMT
References: <<1990Nov28.18333.0@ucrmath.ucr.edu>>
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Randy:

> My board arrived.  Currently I'm pouring over the schematics before turning

Pouring over them?  By the way, would flux remover help?  I tried using
alcohol with little success.  But the board seems to run fine anyway.
Any recommendations?

> on the soldering iron.  I've got a couple of questions someone might be able
> to help me with.
> 
> 1) I note that the DUARTs live at ports 2800020, ...40, ...60, etc.  Yet the
>    address lines going into the 74138 imply that they should be at base
>    addresses ...10, ...20, ...30, etc.  Is the documentation correct?  If so,
>    is this an artifact of the decoding for the ICU?
> 
> 2) I'm interested in a little off-board expansion without going through the
>    SCSI bus (I'm not ready to tackle the design of a smart SCSI controller).

But how about a dumb scsi controller?  From looking at the ANSI spec it looks
like an 8751 should do just fine.  A Z-80 with a PIO should be better.

>    I was thinking of popping off one of the DUARTs, running a couple of addit-
>    ional address lines (and unused decoding lines from the '138)
>    over to the socket and building a daughterboard to plug into
>    the DUART socket.  I'd like to put a couple of parallel ports
>    (perhaps a 6522 or 8255), an 8530 (I want to build an Appletalk
>    interface), and some other devices.  Any problems anyone can warn
>    me about?

Any concern about speed at all?

> 3) Along the lines of question 2, I'd like some additional interrupts.
>    can I cascade another ICU using the daughterboard technique des-
>    cribed above?
> 
> 4) Where do I get documentation for the monitor program?
> 
> 5) Are the source listings available for the monitor?  I'd like
>    to see some code for initializing all the chips.
>