Talk:Burroughs large systems descriptors

C compiler?

Is there really a C compiler for the B5000?

The text makes it sound like Pascal came before ALGOL, and that ALGOL improved on the malloc() system used by C.

I am pretty sure that there wasn't a C compiler for the B5500 that I used in 1967.

Gah4 (talk) 09:40, 23 February 2008 (UTC)

The Pascal compiler was in development in ~1983, when I was at Burroughs. I left in 1984. The C compiler was developed after I had left. So we can safely assume the Pascal and C compilers were available for the A-series machines. Not sure if (or which) older machines were supported. pbannister (talk) 19:53, 7 September 2016 (UTC)

General accuracy

The text mixes up statements about specific machines (B5000) with bit layouts from later members of the architecture (e.g. 20-bit memory addresses). It also refers to the B5000 bit 47 as the P bit, without explicitly warning that that bit numbering is ambiguous (the B5000 numbered the MSB as 0, not 47).

Apart from that, as noted above, there are minor issues relating to allusions to Pascal, C etc. which could possibly be improved. MarkMLl (talk) 09:12, 9 March 2014 (UTC)

I yanked the whole text about the presence bit out of the B6xxx series and put it at the top of the "Details" section, as it applies to all of the machines, and replaced references to "bit 47" with references to the "p-bit" (the fact that, on some machines, it happens to be bit 47, with some particular bit numbering, is not of general interest; it can be covered by the layouts in the sections below). Guy Harris (talk) 06:05, 29 July 2022 (UTC)

the Burroughs Slice compiler

Few know of it, but they remember it. Searches like Slice Burroughs -"bit-slice" find almost no mention, mixed in with many false hits (many things and people are called "slice"/"slicing" and "Burroughs"). One Quora answer confirms several details in the article (I bolded) and extends it somewhat:

Wait, I'm not finished with Pascal yet. Really wanting an Eiffel compiler in environments I worked in, I set to work on a Burroughs (Unisys MCP) Eiffel compiler. Burroughs had a generalised compiler system called Slice (probably the equivalent of LLVM). This separated out syntax analysis, from semantics to intermediate tree structures of programs, to code generator. Guess what – it was all written in an extended Pascal. Scotsman Matt Miller had written the Pascal compiler and was keen for me to do Eiffel. I started with the C compiler (written by Steve Bartels) and adapted it (C was an interesting beast on the Burroughs machines, Steve made it so it had bounds checks, and we discovered a whole lot of problems in [C] programs we ported from quite large and well-known companies, even today!)

— a Quora answer by Ian Joyner at Macquarie University, 2018-08-18

Searches like this might find some more mentions: Unisys "Slice compiler" - A876 (talk) 20:54, 28 August 2019 (UTC)

"This separated out syntax analysis, from semantics to intermediate tree structures of programs, to code generator." - not just in Slice and LLVM; DEC's GEM compiler system (originally developed for DEC PRISM processor and DEC MICA operating system) had such a split, and the GNU Compiler Collection also works in that fashion (I don't know whether the original GNU C compiler did). In addition, the VAX PL/I compiler's backend, the VAX Code Generator, later was used for DEC's VAX C compiler, although I don't know whether it was originally designed to support multiple front ends.. Slice may have been the first such compiler, or one of the first such compilers, but the idea was used elsewhere long before LLVM. Guy Harris (talk) 06:38, 29 July 2022 (UTC)

References