Subject: Re: Falcon serial ports
To: Howard Chu <firstname.lastname@example.org>
From: Leo Weppelman <email@example.com>
Date: 04/14/1997 16:30:41
Howard Chu wrote:
> Hi all,
> a couple of questions about i/o on a Falcon:
> 1) how fast can the standard serial port (/dev/mdm02) be driven?
> Currently I'm using 19200 bps, but I have dreams of ISDN ...
> 2) is there a driver for the `LAN` port, and if so what protocol(s)
> does it support? More dreams, this time involving a transputer ...
> 3) where in the freindly documentation could I have found this out
> for myself? ;>
> Both of the ports are driven by a Zilog 8530 SCC. You can set the clock
> dividers to go up to 230.4kbps if you want. I think that's probably the
> upper limit. I haven't looked at any ISDN modems, do they do speed matching
> for you? (at 2B you're going 128kbps, and most serial ports do 115.2k...)
This might be theoretically sound, but I don't think a Falcon can take serial
I/O at 230.4kbps... I think that 38k4 will be the practical limit. This is
caused by the fact that the 8530 only has a 3 byte fifo. At 230kbps the Falcon
has to serve the 8530 at least once per 1/7850 seconds (assuming it reads 3
chars at once, 1 char == 10 bits).
I have heard rumours that the LAN port does not work. I can't try this out