[net.micro.trs-80] Model 100 as a general purpose modem?

ir682@sdcc6.UUCP (Gerald Steinberg) (10/25/85)

I would like to know whether it is possible to use the Model 100 as
a general purpose modem for other system (such as a dumb terminal,
or a PC).  Please send suggestions and experiences, if any.

johnw@reed.UUCP (John Windberg) (10/27/85)

I feel that project would be fairly easy with
a simple basic program that accesses the port,
remembering that in 100 basic the rs232 can be
reached just like a file.  A null modem
between the rs232 of the 100 and the other
terminal might do it.  Also remember that
there was a flaw in several of the 100's that
render it unable to communicate both ways.  I
tried to use mom's 2000 as a file server for
her 100 and transmissions only went one way
but I forget which way..
oh well so much for thought.
duhhhhhhhh
John B. Windberg
Reed College Portland Or
johnw@reed

usenet@yojna1.UUCP (usenet signon) (11/02/85)

*** REPLACE THIS LINE WITH YOUR MESSAGE ***

No, you cannot use the Model 100 as a general purpose modem.  There is only
one UART in the 100 and that is shared between the modem and the RS-232
port.  PB3 of the 81C55 is the signal RS232C- and is used to gate the output
of the IM-6402 UART to _EITHER_ the modem chip _OR_ the RS-232C drivers/
receivers.  Sorry, you can't have your cake and eat it too.  If you are
interested in hacking, port B of the 81C55 is at address B2h.

As an aside, I have had some fun playing with the UART from Basic.  I have
succeeded in sending 1, 1.5, and 2 stop bits; in sending 5, 6, 7, and 8 data
bits; and in setting the baud rate to just about anything.  I will be happy
to share my information with anyone who needs it.

73 de Brian, WB6RQN
...!bellcore!yojna1!wb6rqn
...cp1!yojna1!wb6rqn