[said Philip] > To: [log in to unmask] > > I can remember using another implementation of a Virtual machine. It was > the San Diego P-code system. The source was University of California, San > Diego Pascal. How thing change in circles. :^{) > > Philip Johnson > Virtual machines - even Ada machines - are nothing new. Here are a few I remember. 1 - Snobol4 was executed on a virtual machine back in the mid-60s. In the early 70s, Robert Dewar implemented the first Spitbol, which was mostly compiled Snobol4. GNAT.Spitbol reimplements most of the Snobol4/Spitbol primitives in Ada. This is a very good set of packages - lets you do Perl in Ada. 2 - The original Ada/Ed executed on a virtual machine. On the Vaxen of the early 80s, this was very slow, as we Ada oldies remember. Much of the work on that "Ada machine" was done by Jean-Pierre Rosen (a Teamer) and Philippe Kruchten (who may still be working at Rational). I have copies of their ENST dissertations (in French). 3 - The original TeleSoft Ada compiler (pre-83, pre-validation) compiled to a P-code that was basically an extended version of the UCSD P-machine. Not surprising - Ken Bowles, who headed the UCSD Pascal project, was one of the technical powers behind TeleSoft at that time. TeleSoft was absorbed by Alsys which became Aonix. Bowles had long since left the company (and retired, I think). 4 - One of the other early Ada compilers - developed by a Pittsburgh CMU spinoff whose name I forget - compiled to an Ada _hardware_ platform. (I think that group may have become Tartan.) 5 - In the early 80s Intel developed a chipset with an OO instruction set, also designed for transparent parallelism - just hang another board on the bus. I think it was called the 840; I just checked the Intel website and their historical section doesn;t mention anything like it. They developed a _really_ interesting extended Ada dialect - this was _before_ the 1983 standard. Much of the OO support presaged Ada 95. They had a keyword 'refines', which had much the same effect as Ada 95 type extension (or the Java 'extends' keyword). The compiler was hosted on a Vax and targeted to this chipset. This interesting architecture disappeared when the x86 family took over. 6 - Don't forget Rational's original Ada machine. The current state of the industry is such that the best way for Ada to take advantage of virtual machines is (IMHO) the jgnat model, which simply targets to the JVM. If you haven't played with it, download it and do so. It's fun to write Java applets in Ada. Mike Feldman