Category : Tutorials + Patches
Archive   : NAT_UART.ZIP
Filename : INTRO.LBT

 
Output of file : INTRO.LBT contained in archive : NAT_UART.ZIP






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.



  3 Responses to “Category : Tutorials + Patches
Archive   : NAT_UART.ZIP
Filename : INTRO.LBT

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. 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/