UCSD Pascal

Created during the latter half of the 1970's, UCSD Pascal is an interpreted version of the Pascal programming language developed at the University of California, San Diego under the leadership of Kenneth Bowles and gets its name from the initials of the university. The system could be run either as operating system that runs the microcomputer, as a layer that takes over the user interface of the computer but relies on a host OS for all I/O running of hardware, or as an ordinary task (i.e. any other program).

The self booting version of UCSD Pascal was alongside MS-DOS and CP/M, one of the three operating systems that were offered for sale for the IBM-PC when it was introduced in 1981, however that appears to have been more symbolic than anything else, as early as 1982 PC customers that had ordered UCSD Pascal when the PC was introduced never got the system shipped to them, so that it appears the system existed in IBM catalogues but there was never any intention to ship them in any volume.

UCSD Pascal implementations

OS/2 tools based on UCSD Pascal

• Cabot UCSD Pascal - Commercial - Discontinued
• Pecan UCSD Pascal - 16 bit only - Discontinued
• ucsd-psystem-xc - Open Source - Discontinued.

OS/2 tools that offer some UCSD Pascal compatibility

• Free Pascal - Open source - Current - Very limited compatibility in more recent versions.
• Extended Pascal - Commercial - Discontinued

While EP is more advanced that UCSD, some extensions present in the system originated in the UCSD system so porting to EP is not too difficult.

Operating systems based on, or compatible with UCSD Pascal

• Advanced Operating System (AOS)
• Apple Pascal - Commercial - Discontinued
• BOS - Commercial - Discontinued
• Cabot UCSD Pascal - Commercial - Current
• Pecan UCSD Pascal - Commercial - Discontinued
• SofTech UCSD Pascal - Commercial - Discontinued

History

The UCSD system is based on ETH Pascal and uses the same p-code interpreter/virtual machine and was initially a straight port of the P2 Pascal system to the types of microcomputer systems that were prevalent at the time in the USA, up until that time most Pascal implementations were on mainframe and minicomputers and it was believed that the system was to large to be used on micros. The French Micral microcomputer however was sold with a Pascal system port a few years earlier despite being based on a lowly 8008 microprocessor and that inspired educational users of the language since it opened up the possibility to give individual students access to a fairly cheap personal computer to develop their software on.

The ETH Pascal system had been built for portability and not speed, and students working on large Pascal programs often clogged up the timesharing systems that the school provided for their use. In some cases the timesharing resources were so limited that students were only allowed to run their software after working hours and even at the ETH a lightweight version of the system called Pascal-S was specifically developed because the ETH's CDC timesharing computer simply could no longer keep up with the volume of work that the informatics students were generating, even if it was running 24/7.