Category : Tutorials + Patches
Archive   : NAT_UART.ZIP
Filename : INTRO.LBT
NS16450 DATA LOOPBACK TEST
This test was developed to run on all IBM AT or AT Compatible
architectures. The only system hardware requirements to run this
test besides the AT are: an NS16450 UART or compatible (not an
INS8250N-B) located in the system at either the COM 1 or COM2
address and a loopback (wrap) plug that connects the serial output
with the serial input of the UART under test. The loopback plug
connects pins 2 and 3 on the standard DB-9 or DB-25 connectors.
The software is on a 360k byte floppy disk and is titled LBT.EXE.
The executable files and the help screens are provided on the disk.
In order to run the software, the previously mentioned hardware
should be set-up and the loopback plug attached to the appropriate
DB connector. The user then inserts the disk containing LBT.EXE
and types LBT [enter]. The test starts and after about 2000
characters are received by the UART a | will be displayed on the
screen. After the next 2000 characters this indication will change
to and continue to alternate every 2000 characters.
The software checks each character it sent (00 - FF) against each
character it received, it also checks for various status
indications occurring within the UART at the appropriate time. All
operations are done under interrupt control. All UART interrupts
are used except Modem interrupts. If the data received is not the
expected data, an overrun error or a break indication occurs a data
error will be indicated. If a Parity error, Framing error or an
inconsistancy between the Interrupt ID and Line Status Registers
occurs, a status error will be indicated. The test will run
continously until an error is detected or until the user presses a
key.
There is a restriction associated with program operation. The
maximum baudrate that the operator can select is 56k baud, however,
this baudrate is limited by the processor speed and the host
system. Tests with various AT compatibles running at 10 MHz
indicate reliable operation on all of them up to and including
19.2k baud. At higher baudrates operation is sytem dependent due
to the overhead involved with processing the interrupts.
The user can invoke a help screen by typing LBT H. There are
several options the user can control, by specifying arguments on
the LBT command line. Each option should be separated by a space
from the previous one. The first option is selection of either
COM1 (default) or COM2 by specifying LBT 1 or LBT 2. The second
option is the number of data errors that the software will
accumulate before stopping. This option is specified by the
numbers 1 (default) through 30000. This option is the second one
on the command line and must be proceeded by the COM designation.
The third option is the baudrate selection. This is specified by a
decimal divisor from 2 through 2304 (default is 12, 9600 baud).
Common divisors are listed on the help screen or in the NS16450
data sheet. The baudrate argument must be proceeded on the command
line by both the COM designation and the data error count
Page 2
designation. An example of the command line used to invoke
operation of COM2 with a program exit after 1 data error and at a
baudrate of 19.2k baud is: LBT 2 1 6. The program will always
terminate after 1 status error regardless of the number of data
errors that are designated.
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/