Pascal not considered harmful - was Re: Rich kids are into COBOL
dave.g4ugm at gmail.com
Fri Feb 20 18:02:00 CST 2015
> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Chuck
> Sent: 20 February 2015 23:00
> To: General at classiccmp.org; Discussion at classiccmp.org:On-Topic and Off-
> Topic Posts
> Subject: Re: Pascal not considered harmful - was Re: Rich kids are into
> On 02/20/2015 02:32 PM, Ali wrote:
> > Excuse my ignorance but then how is a compiler written? I always
> > thought that you would need to know op codes and assembler to write a
> compiler. I.E.
> > you can't write and efficient compiler by using a high level language.
Almost all , so there exceptions, modern compliers are written in a high
level language. Most use LEXX and YACC or their modern equivalents to
generate the program fragments needed to generate the code.
> You have a front-end, which does the lexical work and translates the
> program into some intermediate form, such as a tree. In the middle, you
> have optimization and checking--and finally, you have the back end which
> essentially emits code--but that doesn't necessarily imply that the
> author knows the numeric opcodes or the precise instruction format. Many
> compiler backends feed into an existing assembler, which puts it all
> Knowing the numeric opcodes and instruction format isn't all that it would
> seem to be. I never had much more than a passing familiarity with the
> numeric opcodes of the CDC STAR--given that there was 8 bits for the
> opcode and 8 more "modifier" bits, you arguably had a machine with
> thousands of opcodes. What was hardest and very important was
> committing to memory the *timings* of those instructions, within a
> superscalar, segmented, pipelined vector architecture.
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