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From: gary@apex.UUCP (Gary Wisniewski)
Newsgroups: comp.sys.ibm.pc
Subject: Re: IBM PC AT Hardware Debugger
Message-ID: <301@apex.UUCP>
Date: Sat, 29-Aug-87 16:19:00 EDT
Article-I.D.: apex.301
Posted: Sat Aug 29 16:19:00 1987
Date-Received: Fri, 4-Sep-87 05:31:40 EDT
References: <201@genat.UUCP>
Reply-To: gary@apex.UUCP (Gary Wisniewski)
Organization: Apex Software Corp., Pittsburgh, Pa.
Lines: 40
Keywords: Periscope,debugger
Summary: We like Periscope

In article <201@genat.UUCP> garym@genat.UUCP (Gary Mittleman) writes:
>I have developed a complex PC based voice response system that runs multiple
>tasks under DOS using a home grown context switching system. With additional
>code, our product sometimes hangs the PC. I am looking for a product that 
>allows me to look at memory dumps even though the PC is hung. I once heard of a 
>product called Periscope that hooked up to the XT chip.

I have been using the Periscope III hardware debugger during the the
development of a memory resident product.  I have used the product for
about 2 months and am very satisfied.

Periscope III is very robust.  Periscope always responds, even after some
pretty odious bugs (like overwriting memory from 0:0 upwards for 64K with
a rampant MOVSW).  It is reasonably priced ($900, compared to $2000-3000
for Atron's, I believe inferior, product).  The user interface isn't as
nice as PFIX or CODEVIEW, but I've adapted to it rather easily.  Also,
Periscope is virtually invisible to the application you're debugging.
All memory and code is on the board.

On the down side, Periscope doesn't run on some of the clones.  We had
two SPERRY ITs and an Emulex AT and Periscope wouldn't work on either.  It
turns out that some clones have a slightly different bus architeture.  We
bought a PCs LIMITED 286 for the sole purpose of running  Periscope and
feel it was worth the investment (the board/computer purchase).  In fact,
the cost of the computer PLUS Periscope is still less than the Atron
board and required software.  By the way, Atron has the same clone
problems as Periscope does.  Another minus is the 64K slot of memory
(D000:XXXX, but configurable) Periscope takes up.  This might be
a conflict for those which require EMS or special graphics boards.

Another plus: Periscope is not AT-specific.  It runs on XT's as well as
AT's.  Atron makes a board for each type of hardware.

Periscope has been especially effective at helping us to track down
memory corruption and pointer problems.  Once you master the many
types of breakpoint combinations, it is possible to catch subtle
problems with timing as well as intermittent bugs.

Gary Wisniewski
{allegra,bellcore,cadre}!pitt!darth!apex!gary