Infocom on PDP-11

[woodelf]

Paul Koning wrote:

>Huh?
>
>You're confusing the lack of a hardware stack with the lack of local
>variables.  They are not at all related.
>
>  
>
But the IBM does have INDEX registers that makes emulating a stack easy.

>The IBM 360/370 series doesn't have a stack, and some of its
>restrictions are vaguely PDP-8 like.  Nevertheless, GCC supports C
>(and C++) quite nicely on those machines.  
>
>  
>
But GCC does not need to fit into 4096 words of memory. If you compiled 
C into
a P-code type code I am sure you would have no problems but a very tiny 
memory
space.

>For that matter, Algol had local variables long before C was invented,
>and as you pointed out, there's an Algol for the PDP-8.  (Then again,
>that's not a true compiler -- it compiles to an intermediate form that
>looks very much like a subset of the Burroughs 5500 instruction set.)
>
>And Unix originally appeared on the PDP-7, which you can describe
>quite reasonably as an 18-bit superset of the PDP-8.  (That's
>historically nonsense, but as a description it fits.)  Did C exist
>back then, or did that wait until Unix was ported to the PDP-11?  I
>don't know.
>
>  
>
C was developed around the time Unix was developed but only one they 
ported did they
have a real machine to use. Primeval C ==  
http://www.cs.bell-labs.com/who/dmr/primevalC.html

>Finally, CDC 6000s don't have a stack either, but the first Pascal
>compiler ran on that machine.  Implementing a stack on a non-stack
>machine (or non-stack language like Fortran-II) is a nice elementary
>Exercise for the Student.
>  
>
But if you have subscripted varibles, then you can have stacks and other 
data structures.
you have to do the work the hard way rather than use hardware.

>	   paul
>  
>