On 2013-01-15 18:33, Clem Cole wrote: On Tue, Jan 15, 2013 at 12:05 PM, Johnny Billquist <bqt at softjar.se <mailto:bqt at softjar.se>> wrote: Right. I'm sure that with enough work, you can always do it, but I'm curious on how much work. I have a feeling that compilers written in high level languages rapidly expand their requirements... Its not that actually - IMHO. You can always use overlays and thunks to write code that works on a small address machines, like the PDP-11. I think the problem is that people that used / wanted the language did not need all of the features and frankly time moved on. The languages themselves were just too heavy not the compiler per say - the compilers became heavy to support the language features people wanted. If PL/M or PL/360 had not lost to C (BCPL et al), it might have been different in the case of PL/1. If you note sub-set C compilers for the 8 and 16 bit machines exist or often exist as cross compilers from larger systems. The issue is that 16-bits of data space is >>very<< limiting for a programmer, the code space can be swapped in and out with automatic or managed overlays - but data space is much harder to do. But I'm not talking about cross compilers or subsets. That is a totally different topic. I guess you are arguing that PL/1 is still PL/1, and is not heavy because it's old and not so full of features. That is probably true in itself, but I still suspect that the requirements of a PL/1 compiler written in PL/1 are much higher than a PL/1 compiler written in assembler. The DEC PDP-11 C compiler is not a subset, but is a pretty complete ANSI C. And it is not a cross compiler. But the requirements of the compiler is high, and the code it produces aren't that great. The FORTRAN 77 compiler, as a comparison, produces much better code, and do lots of more optimizations. Heck, even the DECUS C produces better code (that is, when it actually manage to compile anything at all, it's a very retro K&R C implementation). Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol