RE: Cat Box

> Why do you need to handshake? The original CB had no handshaking
> of its switches. THe user flips the switches whenever he wants to.
> There is no latching required.
>
>
> Are you saying that you can only send pulses along the Parallel
> Port and not, for example, bring a line high?
Yes I can bring it high. That wasn't the problem, # of I/O's was. Doesn't
that always seem to be it though.

> This is a different story. If there aren't enough IOs, then we
> need some sort of scheme to write the control signals to the logic board.
This is where we get in trouble. I have like 15 I/O's total on a PP, guess
I wasn't clear on my assumptions of knowledge for everyone else.

> Why not do it serially (i.e. using the Serial Port?) and have the
> software continuously send the settings as part of some loop. There would
> be another line to handshake the data, for a 3-wire interface -- CLK,
> DATA, and WORD. WORD signals a new control word, and CLK clocks the
> individual bits of data into the CATBox. Word can be a 1 CLK pulse, or
> something else...
OK, serial port simplifies the generality of the interface.

Included from following mail
> ----------
> From: aek@spies.com[SMTP:aek@spies.com]
> Reply To: vectorlist@mcfeeley.cc.utexas.edu
> Sent: Friday, July 24, 1998 2:59 PM
> To: vectorlist@mcfeeley.cc.utexas.edu
> Subject: RE: Cat Box
>
> "Why not do it serially (i.e. using the Serial Port?)"
>
> If you do that, i'll sign up to do the mac version
OK, sounds like this is where we are going with it.

> Let me know what you think. If you like it, set the format for
> the bits as you see fit, and then I'll decode them accordingly.
This sounds reasonable. I was trying to avoid having you have to do any
decoding is all. More trying to just replace the switch board as a unit.

So going on this route do you want something like a 64bit int with the
states of all switches represented at mask bits which you store and pass to
the appropriate locations or do you want a "Switch A : ON" type signal (not
text of course) you buffer them internally?

I am assuming we will also have a return signal of all the display bits once
again either packed bits or state change signals.

Let me which way you want to go and I will start specing it out.

> > Looking at the Schematic they appear to just cause the change in data to
> be
> > based on either the rising or falling edge of the signal. If you want
> to
> > check the schem yourself it is the top right part of figure 11.2 (page
> 40).
>
> Not a problem. Those can go in the MACH easily.
>
I was looking at where the switch signals go on the logic board. Self test,
Read/write, 1K, 1Byte, Data, (Active low) Address all go into a ls251 (B2)
8 to 1 multiplexer on the logic board.

Along with a LS139 (F5) which does bank selection for ROM, IN, 6532, Digits,
Segments etc.

The switch matrix stuff is accessed through A3-A8 (by way of LS05 oc
inverter) on the columns and D1-D4 on the rows (through LS368A hex buffer
inverter).

Don't want to tell you your job (especially as this is my second real design
project) but you might be able adapt that stuff when you do the decode logic
for the passed in control info.

David
Received on Fri Jul 24 17:26:00 1998