On Jan 15, 2013, at 12:15 PM, <hvlems at zonnet.nl> wrote: There was a port of the Burroughs Large Systems algol compiler for RT11. I have one on a DECtape I. It compiled test programs that I had written for, and copied from the B7700. Burroughs Extended Algol beats C Bliss hands down as tool to write compilers and os's in. The same one, give or take some edits, I believe. Originally by Barry Folsom, modified by Greg Hosler. RSTS port by Terry Grieb and myself. And yes, originally for RT11 sounds familiar, that would certainly explain why the RSTS port was straightforward. Burroughs Algol is nice for lots of work. For operating systems, there was Espol, which was kept more or less secret because getting access to the compiler meant you could break the OS security... (There is an Espol manual on Bitsavers.) paul