UCSD Pascal - Versions

Versions

There were four versions of UCSD p-code engine, each with several revisions of the p-System and UCSD Pascal. A revision of the p-code engine (i.e., the p-Machine) meant a change to the p-code language, and therefore compiled code is not portable between different p-Machine versions. Each revision was represented with a leading Roman Numeral, while operating system revisions were enumerated as the "dot" number following the p-code Roman Numeral. For example, II.3 represented the third revision of the p-System running on the second revision of the p-Machine.

• Version I

Original version, never officially distributed outside of the University of California, San Diego. However, the Pascal sources for both Versions I.3 and I.5 were freely exchanged between interested users. Specifically, the patch revision I.5a was known to be one of the most stable.

• Version II

Widely distributed, available on many early microcomputers. Numerous versions included Apple II, TI 99/4a, DEC PDP-11, Zilog Z80 and MOS 6502 based machines, Motorola 68000 and the IBM PC (Version II on the PC was restricted to one 64K code segment and one 64K stack/heap data segment; Version IV removed the code segment limit but cost a lot more).

Project members from this era include

• Dr Kenneth L Bowles
• Mark Allen
• Richard Gleaves
• Richard Kaufmann
• Pete Lawrence
• Joel McCormack
• Mark Overgaard
• Keith Shillington
• Roger Sumner
• John Van Zandt

• Version III

Custom version written for Western Digital to run on their Pascal MicroEngine microcomputer. Included support for parallel processes for the first time.

• Version IV

Commercial version, developed and sold by SofTech. Based on Version II; did not include changes from Version III. Did not sell well due to combination of their pricing structure, performance problems due to p-code interpreter, and competition with native operating systems (on top of which it often ran). After SofTech dropped the product, it was picked up by Pecan Systems, a relatively small company formed of p-System users and fans. Sales revived somewhat, due mostly to Pecan's reasonable pricing structure, but the p-System and UCSD Pascal gradually lost the market to native operating systems and compilers.