HP 2000
| Paradigm | imperative |
|---|---|
| First appeared | before 1969 |
| OS | HP 2100 |
| Influenced by | |
| Dartmouth BASIC | |
| Influenced | |
| Cf. Integer BASIC | |
HP Time-Shared BASIC (HP TSB) is an interpreter software system that was sold by the Hewlett-Packard Company in the late 1960s and 1970s, based on their HP 2100 line of minicomputers. The system implements a dialect of the BASIC programming language and a rudimentary user account and program library system. The software was also known by its versioned name, tied to the hardware version on which it ran, such as HP 2000C Time-Shared BASIC and the operating system came in different varieties — 2000A, 2000B, 2000C, High-Speed 2000C, 2000E, 2000F, and 2000/Access. The system is historically notable as the platform that released the first public versions of the game Star Trek.
Except for the 2000A and 2000E systems, the system is implemented using a dual-processor architecture. One fully configured HP 2100-series processor is used for execution of most of the system code and all of the user code and a second, smaller HP 2100-series processor is used to handle the RS-232 serial lines through which the time-sharing users connected. Depending on the hardware configuration, the system supports up to 16 or up to 32 simultaneous remote users. The usual terminal for a TSB system was a Teletype Model 33 ASR and connected directly to the I/O processor or through a modem or acoustic coupler. Account names are a combination of one alphabetic character, followed by three decimal digits, e.g., B001. Privileged accounts started with the letter "A" and had some additional command and program storage capabilities. The superuser account is A000. This scheme allows up to 26,000 user accounts. (In the offshoot system created by BTI Computer Systems accounts beginning with "@" were superuser accounts.)
During execution, user programs are swapped to fixed-head drum memory. When not executing, user programs are stored on moving-head cartridge- or pack-loaded disk storage. Privileged users can also store programs on the much-faster drum. The hard drive was backed up to magnetic tape.
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