PDP-8 Pattern Filler Program

This program fills memory with the given fill value, then increments the fill value and does it all over again. The program finishes when the pattern reaches 0000.

l0,    0000 1007 tad   start  / get starting address,
       0001 3016 dca   addr   / and store into working buffer.
l1,    0002 1015 tad   pat    / get pattern
       0003 3416 dca i addr   / and write into memory (autoincrement)
       0004 5002 jmp   l1     / loop
       0005 2016 isz   pat    / all addresses done, get next pattern
       0006 5000 jmp   l0     / loop
       0007 7402 hlt          / all patterns done, halt.

pat,   0015 0000              / starting pattern, suggest 0000
addr,  0016 0000              / temporary working variable
start, 0017 0020              / start of testable memory, suggest 0020

The running time is 02:11 on real hardware. Given that addresses 0002 through 0005 form the bulk of the work, that places the PDP-8/I's speed at about 0.5 MIPS (2:11 is 131 seconds; the inner loop executes nearly 16 million times (4k locations x 4k patterns); 16 million divided by 131 is about 122k; 4 instructions at 122k iterations per second is 488k IPS).