Pascal not considered harmful - was Re: Rich kids are into COBOL

[Chuck Guzis]

"Bootstrapping" compiler code is quite common.  So, it's not unusual to 
find FORTRAN source code in FORTRAN compilers, etc.  I doubt that many 
compilers are written entirely in assembly nowadays.

For example, back in the late 70s, I put together a business BASIC 
compiler for the 8080/8085.  Theoretically, it was coded in assembly, 
but it wasn't 8085 assembly.  The technique was to code in a 
platform-independent assembly language whose data types and operations 
match the language elements that you're working with--words, numbers, 
tokens, etc.  Then one codes a small emulator in whatever is handy for 
the target system to get code generation shaken out.  Finally, one 
implements the final compiler by taking the specialized machine and
converting them via macros to native assembly.

We coded our emulator and macro processor in PL/M.  They were very 
simple and let us get on with the job of writing a compiler.

When it came time to convert to x86 code, it was a walk in the park, as 
very little of the compiler needed recoding.  The code was subsequently 
moved to Xenix and was in production as late as 5 years ago, even though 
the original company and hardware had been gone for decades.

ISTR that Ryan-McFarland did their implementations the same way back in 
the day.   I still have the original "printed-on-a-Teletype Model 40 
printer" design document that I did.

--Chuck