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From: ST7021@SIUCVMB.BITNET
Newsgroups: comp.dcom.modems
Subject: UARTS and Buffers...
Message-ID: <9104010808.AA05643@ucbvax.Berkeley.EDU>
Date: 1 Apr 91 00:52:03 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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Recently someone brushed on two different UARTs, the 16450 and the 16550.
Can someone give me an idea of what the difference between these two chips
is? It seemed that what brand you get makes a big difference.

MPt (an MS-DOS communications protocol) reports that my Practical Periphreals
PM2400 has a 16450 and that the serial port of my PS/2 model 80, hooked up to
a Hayes V-series 9600, has a 16550. The reason that I bring up MPt is because
the PS/2 tech ref manual says that my mod 80 has a 16450. Anyone have an idea
of what the truth is? I would tend to believe the tech ref, but if MPt has
successfully identified a 16450 I wouldn't think that it would then make a
mistake about the next one.

One last question - why doesn't the everyday serial port have a small buffer
on it? It would seem that putting even a small buffer on the serial port
would be a great relief to a CPU (espically one that is multi-tasking), as
opposed to having to tend to an interrupt everytime a new character comes in.
All at a cost of one or two dollars (or less?). Do modems with buffering
overcome this problem?

Thanks in advance for the help and answers!

Thomas Boehler