PDP-11/40 Test Programmes
Here is a list of small test programs to run on the PDP-11/40 to verify its basic functions.
Here is a list of small test programs to run on the PDP-11/40 to verify its basic functions. These programs are not exhaustive.
Endless Loop
This is a loop that will clear R0 over and over forever. This program is best ran by single-stepping, you would see the addresses 001000, 001002, 001004 repeat over and over.
Address Data Code Switch commands
HALT, 001000, LOAD ADDRESS
001000 005000 clr r0 012700, DEPOSIT
001002 005200 000707, DEPOSIT
001004 000775 br .-4 000775, DEPOSIT
001000, LOAD ADDRESS, ENABLE, START
Increment Loop
This is a simple INC in a loop.
Address Data Code Switch commands
HALT, 001000, LOAD ADDRESS
001000 005000 clr r0 012700, DEPOSIT
001002 005200 000707, DEPOSIT
001004 000005 inc r0 001004, DEPOSIT
001004 000775 br .-4 000775, DEPOSIT
001000, LOAD ADDRESS, ENABLE, START
Light Chaser
This is a simple program that will display a simple bit pattern on the screen and shift it left in a loop.
Address Data Code Switch commands
HALT, 001000, LOAD ADDRESS
001000 012700 mov #1,r0 012700, DEPOSIT
001002 000707 000707, DEPOSIT
001004 006100 rol r0 006100, DEPOSIT
001006 000005 reset 000005, DEPOSIT
001010 000775 br .-4 000775, DEPOSIT
001000, LOAD ADDRESS, ENABLE, START
Debugging
In my system, there was a fault with the rotate left (ROL) instruction. When single-stepping the program it would break out of the console state machine and start running but out of control. The rotate left instruction mainly depends on two boards, the M7231 - Data Paths and M7233 - IR Decode.
The M7231 - Data Paths board contains the ALU and is needed for the shift. The M7233 - IR Decode is used to decode instructions and provides control of the Arithmetic Logic Unit. In my system, the M7233 - IR Decode had failed and a replacement fixed the issue.
Copy Cat
Address Data Code Switch commands
HALT, 001000, LOAD ADDRESS
001000 013700 mov @#,r0
001002 777570
001004 000775 br .-4
001000, LOAD ADDRESS, ENABLE, START
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