Steven Hirsch wrote:
> 
> Have you posted the equations?

Not yet, but there is not much to it.
This is ABEL source.


"Inputs
	!RD_z80			pin 11;
	A7,A6,A1		pin 2,3,4;
	!WR_z80			pin 5;
	A0,A5			pin 6,7;
	!IORQ			pin 9;
	RXF,TXE			pin 16,17;
	

"Outputs
	D0			pin 15;
	wr			pin 18;
	!rd			pin 19;	


Equations
	D0.OE = RD_z80	& IORQ & A7 & A6 & A5 & A1;
	D0 = (RXF & A0) # (TXE & !A0);
	
	rd =  RD_z80 & IORQ & A7 & A6 & A5 & !A1 & !A0;
	wr =  WR_z80 & IORQ & A7 & A6 & A5 & !A1 & !A0;



>> 1. The main purpose - a convenient way to exchange data with a PC.
>> Need some guru's help to make this port accessible as a CP/M
"device".
> 
> If you want support in the OS, it needs to act as PUN: and RDR:.  A 
> better solution might be to write a MEX overlay that treats the USB 
> logically as a UART.

I was looking at the BIOS source you sent me and wondered if it would
be a good idea to just patch READER and PUNCH routines to read/write
the USB port? Or should it be done differently?

MEX seems like a huge overkill... No need to init the modem, dial, etc.
I would like to have small "rx" and "sx" applets to
read/write by xmodem.

> 
> Are there any comm programs available for Windows (or Mac, for that 
> matter) that can use the USB port?

All of them. The module by default uses a "virtual comm port" driver.
Set it as say COM4 and fire up your HyperTerm or whatever.

> 
> I wonder if that setup can be used to emulate an Appletalk interface?  
> Have to give it some thought.
Now we are way over my head.

-Alex.
--- SBBSecho 2.12-Win32