Path: utzoo!utgpu!watmath!watdragon!trillium!bjhicks
From: bjhicks@trillium.waterloo.edu (Barbara Hicks)
Newsgroups: comp.sys.atari.st
Subject: electronics help sought
Message-ID: <13050@watdragon.waterloo.edu>
Date: 5 Apr 89 04:34:34 GMT
Sender: daemon@watdragon.waterloo.edu
Distribution: comp
Lines: 29


Hello fellow netlanders, I have need of some electronic assistance.  The
problem is as follows:

I need a board for an ST that will monitor the address lines and FC0-FC2 and
perform a range check for each User Data or User Instruction fetch.  I would
like to have two separate ranges, one for Data and one for Instructions.
Ideally I would like to check all 24 address lines, but I would settle for
just the upper 16.  If the address is out of range on either type of fetch,
a bus error will be generated.  The bus error MUST occur fast enough to prevent
a data write from actually occurring.  Also, I plan to grab the address lines
from the MMU and I would like to have the whole works fit under the shielding.
Oh, and last but not least, these ranges must of course be programmable via
software (like writing to $ffxxxx or some such thing).  If anyone out there has
any thoughts on the matter or any thoughts as to where to find some help,
please Email me and I will summarize for the net if there is sufficient
interest.

I do not expect to find this device to be in existence and I am quite willing
to hack it all together, but I have not played around with electronics much
since high school.  I don't know what wonderful chips are available these days
and I would welcome any suggestions.

Thanks much,

-- Barbara (bjhicks@trillium)

PS  please don't hesitate to mail me if you have any advice as I only have this
    account for another few weeks.