RE: Cat Box

I have been looking over the Cat Box schems with an eye on what I can do for
the Switch Board.

The inputs on that board are:
A 4 row 6 col switch matrix composed of
16 position kbd
        (0 / 4 / 8 / C col 1)
        (1 / 5 / 9 / D col 2)
        (2 / 6 / A / E col 3)
        (3 / 7 / B / F col 4)

(Col 5 below)
"Error Data Display" Game / Tester 2 pos switch
"Address Increment" NO momentary switch
"Data Set" NO momentary switch
"Tester mode" (R/W) / Signal analyzer 2 pos switch

(Col 6 attached to row 3 / 4 only)
"Read / write mode" Static / (off) / Pulse 3 pos center off switch

The "Data probe" logic probe is a bit of circutry which is primarily used to
fee the active low SRDATA signal at pin 11 of C2 on the logic board. There
needs to be some circutry used to issolate the CB from the circut under test
but probably not any where near what they have now as they are also
supporting the logic probe lights and clocking.

Then there are some stand alone switches:
"Tester reset" NO momentary switch
"Tester self test" 2 pos switch
"Read / Write" 2 pos switch
"Bytes (1024 / 256 / 1)" 3 position center off switch
"DBus source (Data / Active high Address / Active low address)" 3 position
center off switch

The last section of switches are the signal analyzer triger control switches
which XOR (using a 74LS86) the input signal with a pullup high or gnd.
"Start" 2 pos switch
"Stop" 2 pos switch
"Clock" 2 pos switch

Then finaly there is the display section
6 7-segment leds (with decimal point) 4 for address 2 for data
3 stand alone leds arranged so they act as the F , G and dp segments of a
7th LED
        Looping (F)
        Unstable Signature (G)
        Compare Error (dp)

Then there is a stand alone led just hanging off an input from the logic
board called "Gate" (pin 1 of the interconect)
These are all driven by signal from the logic board thru a driver
transistor, the selection between the leds is done by a 74LS42 BCD to Dec
decoder

Then the final part of the whole thing is:
"No clock" led which is being fed by half 74123 retrigerable monostable
multivibrator.

Now what does this get us. If we were to try to build a computer interface
I am thinking a bi-directional parallel port interface as this gets more
lines thru at one time and that goes along well with the parallel data
nature of the leds.

So we would have to have a set of latches to pretend they were the switch
matrix. Not too tough.
And we would have to have a set of latches to pretend they were the
display's. Once again not to bad.

The XOR's for the probes are still needed but could perhaps be moved into
the "chip". Joe?

I am still in the brainstorming stage of this so let me know if any of you
brain trust types has any thoughts.

David
Received on Fri Jul 24 14:06:29 1998