Whither the Stack?

The programmer is likely to ask “Where is the stack?”. There was no stack in 701 programs. The early Fortran computing platforms had no stack either conceptually or in fact. In fact the stack was such a vital improvement to computing (Algol 60?) that today one must be carful not to lose it.

A computation involving many objects in Keykos usually conforms to the early Fortran pattern where each involved object is at any instant, waiting, running, or available. See this. The waiting domains are linked together by return caps into what might be seen as a stack. This pattern precludes an object appearing twice on the chain. Modern computing patterns are full of recursive algorithms. Keykos has its share of recursive algorithms. They appear in these forms: