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From: U39648@uicvm.uic.edu (From The Mind Of)
Newsgroups: comp.sys.ibm.pc.misc,comp.dcom.modems
Subject: Re: 4.77MHz PC sufficient for 19200 bps modem?
Message-ID: <91171.105841U39648@uicvm.uic.edu>
Date: 20 Jun 91 15:58:41 GMT
References: <1991Jun18.201125.6198@cs.cmu.edu>
Organization: University of Illinois at Chicago
Lines: 26

>A housemate has an original Big Blue IBM PC, running at the blazing
>speed of 4.77MHz.  We want to use this as a dumb terminal to access
>our university workstations.  The university offers 2400 bps service
>with MNP level 5, and a 9600 bps or 19200 bps MCN service using DOV
>modems.  We'd really like the extra speed if possible.  Is the PC
>going to be able to keep up with 19200 bps?  How about 9600 bps?  It
>must be at least 5 years since I touched a PC, so I've lost any idea I
>may once have had for the speed of these beasts...
>
>Oh, and if the PC *can't* keep up, what sort of motherboard upgrade
>would we need?  10 MHz 8086?  80286?
 
Your PC should be able to keep up if you replace the UART that
controls your serial port.  It's probably an 8250, so you can
replace it with a NS16550A directly, which has a FIFO buffer to
help handle high speed transfers, especially on slower machines
or fast machines running multiple tasks.  This chip is inexpensive,
and you should be able to get one for under $20.
 
- Darius
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