Simulator Bookkeeping

Execution begins at the instruction after the entry point, INTRPT. Startup code loads the registers and then falls into the fetch-execute loop at INT1. The interpreter counts instructions as it runs and will exit through INT0 when it counts down to zero. The program-stop (PS) at INTRPT will have been replaced by a jump to the caller as part of the the return-jump (RJ) calling sequence.
 INT0     RJ     SAVREG  
          RJ     RESREG  
 INT1     ZR     B2,INT0 
          NG     B2,INT1.1 
          SB2    B2-B1 
 INT1.1   ...

PDP-8 Simulator
© 1975, 1998, Ward Cunningham
all rights reserved