Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!FRESE51.BITNET!DUJARDIN
From: DUJARDIN@FRESE51.BITNET
Newsgroups: comp.sys.atari.st
Subject: Reading from a data stream
Message-ID: <9002190807.AA24495@ucbvax.Berkeley.EDU>
Date: 19 Feb 90 08:08:12 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 23
X-Unparsable-Date: 17 FEB 90 14:38:48.33-GMT

In INFO-ATARI16 Digest V90 #211, Ron DiNapoli wrote :

>I am interested in reading a serial stream going at 230K bits/sec into
>my ST.  I've been thinking of using the drive port (documentation says
>it moves at 250K bits/sec) but I am not sure it will work.  I'd like to
>avoid using the internal expansion bus...  any ideas?

Why wouldn't we use the RS-232 port for such speeds ? I know that this port is
usually used at baud rates <= 19200, but if you read the specs of the 68901,
you
see that it can be much faster : there's only a bit to change in a register,
and
things go 16 times faster. The trouble is that the documentation states that
such speeds should only be used for synchronous communications, and i don't
think it is available on the ST. There seems to be no way of adressing the
RS-232 port with the DMA (!).
Of course i did a few tests, and it seems to work allright. Maybe it caused
some
damage to my hardware (i didn't notice anything yet !), but 57600 bit/s works
fine. I did the test between my ST and a PC (incidentally, RS 232 ports on PCs
can work at 115200 bit/s - there's a file exchange program using this speed).
You can set up this speed with Rsconf, and even use bios buffers ! The maximum
speed is 614400 bit/s : not so bad, isn't it ?