6 Aug
2005
6 Aug
'05
2:31 p.m.
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.