🚀 go-pugleaf

In article <15564@oberon.USC.EDU> kurtzman@pollux.usc.edu (Stephen Kurtzman) writes:
| In article <8513@polyslo.CalPoly.EDU> dorourke@polyslo.CalPoly.EDU (David M. O'Rourke) writes:
| >  I hope this helps.  But if you look at processor design you can sometimes
| >see what language it was originally designed for by the instruction set
| >it has.
| 
| Conversely, if you look at a language you can sometimes see for which processor
| it was designed. As noted by others, c was originally designed for the PDP-11.
| Because the PDP-11 has pre-decrement indirect, and post-increment indirect
| addressing modes, c has ++ and -- constructs to take advantage of the PDP-11
| architecture.

I believe that the pre- and post- inc/dec operators were already present
in BCPL and B, and that is where they came from.  However, the implicit
conversion from float to double in (K&R) C for all floating-point
operations was due to the PDP-11, on which it was difficult to switch
between single and double-precision modes. 

| Likewise, the car and cdr of LISP have their analogues in the
| architecture of the machine on which LISP was first implemented. There are
| likely other examples, but I'll leave that to the language specialists.

Not really -- CAR stands for "Contents of Address Register" and CDR
stands for "Contents of Decrement Register" on the IBM machine that the
first LISP interpreter was written on, and definitely are not
analogues to the car and cdr operations.  Lisp machines came much later. 

	-- Tim Olson
	Advanced Micro Devices
	(tim@crackle.amd.com)