Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ucsd!rutgers!mit-eddie!bbn!rochester!pt.cs.cmu.edu!b.gp.cs.cmu.edu!Ralf.Brown@B.GP.CS.CMU.EDU
From: Ralf.Brown@B.GP.CS.CMU.EDU
Newsgroups: comp.sys.ibm.pc
Subject: Re: ISDN
Message-ID: <23056a96@ralf>
Date: 14 Aug 88 11:25:26 GMT
Sender: netnews@pt.cs.cmu.edu
Lines: 31
In-Reply-To: <6108@bigtex.uucp>

In article <6108@bigtex.uucp>, james@bigtex.uucp (James Van Artsdalen) writes:
}[...] Mess-DOS
}rolls over dead at the thought of 9600bps (interrupt latency on
}extended memory on slow machines), much less 8Kbytes/sec!  I rather

Better not tell that to all the 4.77 MHz IBM PC's running USRobotics HSTs at
9600 or even 19200....

}[...]  Even
}using an NS16550A serial chip with the 16 byte FIFO isn't going to cut

6400 / 16 = 400 interrupts per second.  Sounds quite manageable to me, even on
a 4.77 MHz 8088 box.  When I still had my Eagle PC (4.77 8088), I used to run
a print spooler that sped up the clock tick interrupt to 2330 times per
second!  (in order to pump >1000 bytes/sec of graphics data to the printer)
The PC could even have handled 4660/second, as the spooler consumed about 30%
of CPU cycles.  If a serial port handler can't hack 1/12 the interrupt
rate, something is wrong....

}[...] not that the Mess-DOS file system is
}currently good for sustained 8K/sec anyway.

Even if DOS is quite sloppy and needs two rotations to write a track on a
floppy disk, it can write two tracks (9K) in 0.8 seconds, which sure looks
like more than 8K/sec to me....  It's only when the floppy disk gets quite
fragmented that DOS might have trouble getting 8K/sec onto the floppy
disk--but that's caused by the floppy and not by DOS.
--
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