Analog modem emulator?

[Tim Shoppa]

> The Apple Serial Card I have doesn't have any UART, or shift
> registers, or anything like that.  Just a few TTL chips to make
> a 1 bit I/O port [...]

This card was used mainly (but not exclusively!) to drive serial
printers.  I think the firmware is expressly half-duplex.

A far more common and useful card is the slightly later "Super
Serial" which has a 6551 UART IIRC.

I don't know of any communication programs which supported the
non-super card.

I think there may have been a revision to the original UARTless
serial card's firmware that allowed it to detect flow-control
characters from the printer (e.g. XON/XOFF) even though it
was half-duplex.

Tim.