(Called the DSSR group at that point om time, if anyone wants to look anything up.) This entire toolchain, including all the source, has been preserved; the BCPL compiler, the linker ('bind', itself written in BCPL), and a number of tools (including an extra one, 'ldrel', written by the CSR group on the 5th floor). I have in the past put up some pieces for download, but I never got around to doing the whole thing, as there didn't seem to be any interest. We (CSR) started working with the toolchain because it included support for MACRO-11 (the BCPL compiler could produce either MACRO-11 or UNIX assembler source as output). That toolchain used a relocatable formet, .rel': http://ana-3.lcs.mit.edu/~jnc/tech/unix/man5/rel.5 that I think was based on one DEC had done. CSR was working with a semi-real-time operating system, called 'MOS': https://gunkies.org/wiki/MOS_operating_system for the PDP-11, that we'd gotten from SRI. (MOS was used a lot in early work on the Internet; e.g. all the BBN 'core' routers used in the early Internet used it, after the very first ones [written in BCPL, oddly enough], which had used ELF: https://gunkies.org/wiki/ELF_operating_system but BBN soon switched to MOS.) MOS was written in MACRO-11; we started working with MOS with the same toolchain SRI had used for it, which ran on TOPS-20. I soon decided I'd rather work on our group's PDP-11, initially a PDP-11/40 running a clone of the DSSR system (the first UNIX at MIT). So, we started working with the MACRO-11, and bind, on UNIX. I then decided I'd rather write code for our PDP-11 packet switches in this nifty language called C, used on UNIX, which nobody else knew about (at that point). The first step was to write 'ldrel', to convert a.out files (produced by the C compiler) to .rel files, so 'bind' could work with them. After a while, we decided we'd rather use 'ld' as our linker (I think because it supported demand loading from binary libraries, so we didn't have to manually specify every file to link). The DSSR group had long ago written 'relld', which converted .rel files (produced by MACRO-11) to a.out files, so that was pretty easy. There seems to be a version of the BCPL compiler which produces 8080 code. It looks like that pre-dates the 8086 C compiler from MIT (the 8080 C compiler was not done at MIT). (I just ran across a 6502 emulator written by Rae McLellan of DSSR; he and they seem to have done a lot of work with various micros. It may not have all the pieces it needs to work, though; it seems to need "/usr/simulators/s6502/s6502.body" from the DSSR machine.) Pity I didn't save a dump of that machine too; I was once looking for the source of the Algol interpreter, written on the Delphi machine, and made to run under UNIX, and I asked Steve Ward if any dumps of the DSSR/RTS machine still existed, and he thought not. So we have the binary of that Algol interpreter, but not the source. Of course, it was probably written in MACRO-11, so a disassembler would produce a reasonable facsimile. And I should ask Lars if the backup tapes of the DSSR/RTS machine went to the MIT archives - they might well have done, and Prof. Ward just didn't know that. Noel