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1992-09-22
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CHK_UART V1.0
Copyright (C) 1992 Marc Genois.
All Rights Reserved.
What CHK_UART do ?
==================
CHK_UART is an utility to allow you to check the UART type used by your serial
ports.
The program chk_uart is able to detect the following UART :
-8250
-8250A or 16450
-16550 (no FIFO buffers)
-16550A (with FIFO buffers)
-IBM UART (with DMA and FIFO)
How to use it?
==============
Usage : chk_uart [com #] ...
ex : 'chk_uart 1 2' will check for COM1 and COM2
Program revision
================
92-09-22 Release of version 1.0
C source code is available via :
Fidonet : Marc Genois 1:240/20
Compuserve : 72570,1513
Marc Genois
Sainte-Foy, Québec
Canada
IBM PC UART history
===================
The original UART used on a PC was the 8250 chip. The first "upgrade" was the
16450, used in the PC AT. The 16450 provide faster interfaces between the UART
and the processor, but it's only functional difference from the 8250 was the
addition of a scratch register where the processor could store a byte of data.
Then the 8250A was introduced in the PC Convertible, the first IBM laptop. The
8250A if functionally identical to the 16450. In 1987, with the release of the
PS/2 models, come the 16550 UART. But the UART had a bug that disable its main
feature : FIFO buffers. So came the fixed version, the 16550A. Recently, IBM
has introduced a new UART in it's PS/2 model 57, 90 and 95. This new UART is
fully backward compatible to the 8250 and feature : FIFO queues, DMA transfer
and speed up to 345,600 bps.
For high speed (9600 and up) a 16550A chip is recommanded.