JOSS (acronym for JOHNNIAC Open Shop System) was one of the first interactive, time-sharing programming languages. It pioneered many features that would become common in languages from the 1960s into the 1980s, including use of line numbers as both editing instructions and targets for branches, statements predicated by boolean decisions, and a built-in source-code editor that can perform instructions in direct or immediate mode, what they termed a conversational user interface.
JOSS was initially implemented on the JOHNNIAC machine at RAND Corporation and put online in 1963. It proved very popular, and the users quickly bogged the machine down. By 1964, a replacement was sought with higher performance. JOHNNIAC was retired in 1966 and replaced by a PDP-6, which ultimately grew to support hundreds of computer terminals based on the IBM Selectric. The terminals used green ink for user input and black for the computer's response. Any command that was not understood elicited the response .
The system was highly influential, spawning a variety of ports and offshoots. Some remained similar to the original, like TELCOMP and STRINGCOMP, CAL, CITRAN, ISIS, PIL/I, JEAN (ICT 1900 series), Algebraic Interpretive Dialogue (AID, on PDP-10). Others, such as FOCAL and MUMPS, developed in distinctive directions. JOSS also bears a strong resemblance to the BASIC interpreters found on microcomputers in the 1980s, differing mainly in syntax details.
History
Initial idea
In 1959, Willis Ware wrote a RAND memo on the topic of computing in which he stated future computers would have "a multiplicity of personal input-output stations, so that many people can interact with the machine at the same time." The memo gained the interest of the US Air Force, Rand's primary sponsors, and in 1960, they formed the Information Processor Project to explore this concept, what would soon be known as time-sharing. The project was not specifically about time-sharing, but aimed to improve human-computer interaction overall. The idea at the time was that constant interaction between the user and the computer in a back-and-forth manner would make such interactions more natural. As JOSS director Keith Uncapher later put it:
A formal proposal to develop what became JOSS on the JOHNNIAC computer was accepted in March 1961.
JOSS-1
JOSS was implemented almost entirely by J. Clifford Shaw, a mathematician who worked in Rand's growing computing division. It was written in a symbolic assembly language called EasyFox (E and F in the US military's then phonetic alphabet), also developed by Shaw.
The JOSS system was brought up formally for the first time in May 1963, supporting five consoles, one in the machine room and another four in offices around the building. The early consoles were based in the IBM Model 868 Transmitting Typewriter, as the Selectric had not yet been introduced to market when development began. The first schedule was published on 17 June, with JOSS running for three hours from 9am to 12 every day. It was declared fully operational on eight terminals in January 1964. The final version was deployed in January 1965.
By this time the JOHNNIAC was already over a decade old, and its tube-based logic was never highly reliable to begin with. Even when it was working well, the system became so popular it quickly bogged down. Users were enthusiastic, one stated:
Another put it more succinctly:
JOSS-2 switchover
In May 1964, the decision was made to look for a new machine to replace the JOHNNIAC and dedicate it entirely to running an expanded version of JOSS. The machine would also have to support new terminals made to Rand's specifications, and be delivered by 31 October 1965.
A total of nine bids were received for the new machine. Digital Equipment Corporation (DEC) won the contest with their new PDP-6 system, and Air Force funding was released for the purchase. DEC also agreed to build thirty terminals based on the IBM Selectric typewriter modified with a special mechanism to advance to the next page in a fan-fold paper feed. Several other portions of the overall system were delivered from other companies.