Re: Apple ][+ - IBM linkup...

[dpscholn@mtu.edu (Dan P. Scholnik)]

Eugen Fournes (fournes@nucleus.com) wrote:
: I was wondering if there was any way to connect up a 1-way link
: (Apple to IBM) through my existing printer port/card?  The card is for
: a SilentWriter ][ (thermal printer), and has a standard 9-pin "D"
: connector.  I'm not afraid of breaking a few pins on a cable to make
: this work, but I don't want to risk blowing anything in either machine.
: 

	I actually almost did this with an Epson APL parallel board. I never got
around to actually finishing the project since I picked up a serial card, but
this is how it would work: The Epson card has 8 output data lines and 2 others,
a strobe output to the printer to let it know that there is data, and an ack
(acknowledge) input from the printer which tells it that the printer is done.
The data lines can be connected to the status and control inputs of the IBM
parallel port as can the strobe, and one of the IBM's data out lines can be
hooked up to the ack. Then you need to write routines on the IBM side to emulate
the printer, receiving the data and pulsing the ack line after the strobe
line is pulsed. Then on the Apple side you need to send 8-bit data to the 
printer port. It requires some low-level programming, especially on the IBM
side.
	Now that I read your post again, I see that the connector is a 9-pin,
which means it must be serial, and everything I wrote is moot. You could try
writing a simple serial receive routine on the IBM and then just send random
bytes out the printer port on the Apple, and see what comes out. If you get
all the relevant parameters (baud, parity, etc.) set up right you can probably
use the printer card like a serial card (which is what it is). Check your 
manual for the pins on the printer card and see if they are standard RS232.
	If you want any specifics, just mail me or post.

Dan Scholnik
dpscholn@mtu.edu