Re: Need info on old serial card

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <437rhg$kg6@iitmax.acc.iit.edu>,
Ed Federmeyer <ed@iitmax.acc.iit.edu> wrote:
> I have an Apple //e, and a "serial interface card" (from Apple).  It is not
> the "super serial card", but the older one.
> 
> As I understand it, there were originally two serial cards:
> "serial interface card" and "serial communications card".

Yep.  I don't know anything about the latter, but the former is only
useful with a serial printer.

> Can I use the NON-communications card with a modem, or will it only
> work with a serial printer?  How about if I use a null-modem between
> the computer and the modem?

Not likely.  The Apple Serial Interface Card only supports half duplex
communication (it cannot transmit and receive simultaneously).  It
doesn't even have a UART - the actual serial transmit/receive is done
by outputting or inputting the bits from an I/O port, with
software-driven timing.

Obviously, it doesn't support interrupts, and is not compatible (at
the hardware level) with the Super Serial Card, which rules out about
95% of comms software.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand