HP ET8855 - Logic Analyzer Demonstration System

From: Joe <rigdonj_at_cfl.rr.com>
Date: Sun Sep 8 17:42:01 2002

Tony,

   I've seen stuff like that for logic analyzers. They're just small scale computers and are used to teach/demonstrate how to use a logic analyzer. I have instructions for one here somewhere (from Gould I think). I don't have the device but the docs show the schematic and contain the listing of the EPROM on it and it's VERY simple. You can make it "run" a short program that's in EPROM and you use that to demonstrate how to setup the LA to trigger when certain data appears and also set to trigger on the Nth appearance of certain data. The EPROM also has some sections with all 0s and alternating 1s and 0s and that's used for some other demo but I don't recall exactly what they were for.

  The BNC connector on your's is almost certainly to supply 5 VDC for a HP logic probe. HP built all (or some) of their probes to get power from a BNC connector and included the BNC power point on many of their instruments.

>"reset", "cnt up", "cnt dn", "clear" and "stop".

   Sounds like the SW on the board just has a simple counter program. Reset the CPU so that it restarts at address 0. Make it count up or down, clear the counter without resetting and stop the counter.

   If you don't need it. I'd like to play with it.


   Joe


At 01:27 PM 9/8/02 -0400, you wrote:
>I recently picked one of these up. It's a flat panel with a pair of
>boards, one marked 8080 and the other marked 6800. Both boards have ZIF
>processor sockets (the one on the 8080 board is empty). There's a set of
>four seven-segment LEDs on the 6800 board. The panel includes a pair of
>toggle switches (run/hold below the 8080 board, run/reset below the
>6800) There's a bnc plug marked 'logic probe' and a set of switches marked


>"reset", "cnt up", "cnt dn", "clear" and "stop".
>
>Does anyone have any idea what it's for?
>
>-- Tony
>
>
Received on Sun Sep 08 2002 - 17:42:01 BST