Newsgroups: comp.sys.handhelds
Path: utzoo!utgpu!watserv1!watmath!dabowman@systems.watstar.uwaterloo.ca
From: dabowman@systems.watstar.waterloo.edu
Subject: (none)
Message-ID: <9103272320.AA05403@watserv1.uwaterloo.ca>
Sender: @watmath.waterloo.edu
Organization: University of Waterloo
Date: Wed, 27 Mar 1991 18:20:56 EST
Lines: 31

===============================================================================

I am looking for some pointers to information on the HP28S scientific
calculator's hardware. Specifically, I wish to give it serial input
capabilities.

I've seen the reviews on HP28COM, but would like to do this myself.

Has anybody     1) done this
                2) know of someone who has/a book which describes it
                3) got any opinions on what is a good method

My thoughts on the subject were to maybe bridge one of the keys
and use an assembly program to read it.

How about the IO ports -- is the IR port write-only? (ie IN/OUT instructions)

While I have it open, is it feasible to add a 32K ram chip?

Any and all info, advice etc would be appreciated. (It was hard enough to
figure out how to open the case).

Thanks for reading.

Don.

email DABOWMAN@SYSTEMS.WATSTAR.WATERLOO.EDU ||
                DABOWMAN@SYSTEMS.WATSTAR.UWATERLOO.CA



