This is G o o g l e's cache of http://history.dcs.ed.ac.uk/history/ChrisWhitfield as retrieved on 5 Sep 2006 20:18:43 GMT. G o o g l e's cache is the snapshot that we took of the page as we crawled the web.
The page may have changed since that time. Click here for the current page without highlighting.
This cached page may reference images which are no longer available. Click here for the cached text only. To link to or bookmark this page, use the following url: http://www.google.com/search?q=cache:j2LkgdOWQ4QJ:history.dcs.ed.ac.uk
Google is neither affiliated with the authors of this page nor responsible for its content.
I've lightly edited two emails from Chris Whitfield together, to summarize his recollections:
Things that spring to mind ... and I hope I still have m/c readables ....
PDP-8 imp syntax checker dating from when paper tapes were punched on exceeding unreliable teletype 33s for transmission to Manchester. This thing scanned the tapes and attempted to locate as many mispunchings as possible. Summer 1966
PDP-9 Inktronic printer driver .... the dreaded Inktronics
PDP-9 Editor
PDP-9 bootstrap tape .... booted both manufacturers OS and Hamish D's Imp System. 10 instructions long (1" of tape!) so it could be taped in a loop and left in the reader.
Text Layout program .... used for 2 years by ERCC.
PDP-9 "interpreter" .... checked student programs dynamically. Checked each instruction before allowing it to be executed. Prevented beginning assembler coders wasting time trying to find faults. Could check only part of a program so was of practical value quite apart from helping students.
Mouses Operating System with Peter Robertson. Used heavily at Moray House (Moray 'ousesystem !) and by CS undergraduates. I still have the complete source of this on a 1600 bpi 1/2" tape which may or may not still be readable.
Just been talking with Peter Robertson. We're both happy for the source of the whole Mouses system, compilers and other support software to be made available. Depends on that 1600 bpi tape I have still being readable though.
Yet another assembly code version of ECCE for Perkin-Elmer 32-bit mini.
I infiltrated Newcastle University's purity in 1972 or so by porting the ERCC Imp and Fortran compilers to MTS. The professional support people there, staunch handcoders to a man, were completely gobsmacked at the code IMP could generate. Their view of high level languages was utterly conditioned by things like AlgolW and PL360.
Incidentally, the
original ECCE was written by Alan Freeman for the PDP-8 in around 1964. I think he's a financial analyst in London now ... at least I saw someone called Alan Freeman on a financial talk show on the box who was his spitting image.
This turned out to be a slightly corrupted memory dump... Alan Freeman did indeed design an editor before Ecce, and it did introduce a few of the ideas which made Ecce so powerful (such as conditional execution) but Alan's editor was rather primitive in comparison and definitely not a forebearer of Ecce. We have however found the source on paper tape and as soon as we can download it, you'll be able to judge for yourself. We also have scans of a very poor photocopy of a typed/handwritten manual for Alan's editor. -- Graham
Alan Freeman or a PhD called Brian Read .... I think Alan.... was responsible for a PDP-8 game .... ca. 1965. Push buttons, a CRT display and a loudspeaker. Two highly stylized tanks drawn on the CRT. You chase the other tank and fire your gun at it with much bleeping from the loudspeaker. All 2D and crude by today's standards .... but must have been one of the early examples of such a thing?
(I remember playing this. I think it predated arcade games like asteroids. The tanks were in a very similar vein to Asteroids but it was a much simpler game. Two player, however! -- Graham)
I have a fair pile of the original departmental reports. Unfortunately about half were chucked only 6 months ago so those left tend to reflect my particular soft spots.
An outfit called the English Language Research Unit was (I think) merged into the newly formed Computer Science Dept. bringing Hamish Dewar and Paul Bratley. ELRU had produced a program which could produce all the parses of ambiguous English sentences more or less in real time. Consider "He rolled up the red carpet"! The interesting thing about this was that it had a fixed dictionary of only about 600 words .... no content words. I don't know where Paul Bratley ended up.
David Rees was a PhD student at about this time. He designed a string handling language called Astra and wrote a compiler for it. These were in essence the string handling extensions to Atlas Autocode which were subsequently incorporated into IMP. He may also be able to fill in details of what Paul Bratley did.
I've asked DJR about Astra -- Graham
EMAS had substantial performance advantages over standard ICL operating systems running on the same hardware. It in fact ran ICL programs on a VME emulator faster than the real VME. I still wonder whether the "Director" based scheduling strategy and mapped filesystem was in fact more effective than the strategies used in currrent day multi-programming systems.
IMP in its day was practically unique in being a language with substantial diagnostic assistance which could also be used "in anger" as a fast economical systems language. Subsequently Ada is perhaps the only mainstream language of which this can be said?
The "3rd pass" - consolidation phase - of the Peter Robertson compilers was again in its day unique. I remember being told at Cebit about 8 years later by a very proud compiler writer that they'd dreamed up this wonderful way of fixing short jumps -- which featured heavily in their advertising. Peter's compilers did far more long before and the Mouses 32-bit Perkin-Elmer variant did a whole lot more again.
Prof Wulf's "Optimising Compiler" book contains a PDP-11 coding sequence for Ackermann, generated by his compiler, which he asserts was optimal because he himself could not handcode it more tightly. Unfortunately Peter's PDP-11 IMP compiler takes 2 instructions off the "optimal" code displayed in the book.
