On Fri, 27 Jul 2001, Phil Frost wrote:

> No, just the protocal the mac uses to transfer on the serial line, the pins,
> the handshaking, etc. PCs use rs-232 and macs use rs-422. rs-422 is a twisted
> pair version of rs-232 that is tremendously faster. However, to connect an
> rs-232 to a rs-422 requires a common ground and some nasty klunking, and in
> the process you end up with a much slower connection (115200bps maybe) and
> a few missing signals, most noteably RTS, request to send, which asks the
> other end to stop sending either so the recieve buffers can be emptied or
> data can be sent. Anyhow, this problem can be avoided by using DTR in lieu
> of RTS. The moral of the story is that PCs suck and macs rule.

You've said a number of correct things, and a few not-so-correct things in
there. I certainly agree with your last sentance.

RS-422 doesn't make a connection faster, it makes communication at a given
rate possible for a longer distance. You can get both RS-232 and RS-422
connections to got 230400 bps, just the RS-422 one will go farther. My
estimate is something like 10 to 100 times farther. RS-232 will do fine
for a modem cable (the modem is what, like 18" away?), but I agree, it'll
suck if you want to go down the hall to a printer.

Also, "loosing connections" when going to RS-232 is a bit of a misnomer, I
think. We "loose connections" compared to RS-232 the moment we go out the
back of the computer. We have only one outgoing flow control line, DTR.
RS-232 vs RS-422 doesn't matter - Apple didn't sell us the pins. :-)

Take care,

Bill