What does PUSHJ do? (was Re: was "C on the PDP-8 ... ") - test-drb@ccmp.vtda.org

11 May 2005

It was thus said that the Great vrs once stated:
...

    What does PUSHJ actually do?  I remember
reading about it in Steven Levy's
 Hackers, but never got what was so special about it.  
 PUSHJ does a CALL, using a software implementation of a stack, which allows
 the target subroutine to be recursive.  JMS stores the return address in the
 entry point, so it won't do (without help) for recursive routines.
 (Similarly, POPJ is like RET.) 
  Oh, PUSH-JUMP.

  -spc (Okay, that makes sense now ... )