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HP Time-Shared BASIC (HP TSB) is a BASIC programming language interpreter for Hewlett-Packard's HP 2100 line of minicomputers. The system implements a dialect of the BASIC 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.

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, while 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, such as the ability to use the Storage Drum, or to prevent a program from being listed ( Protected ). The superuser account is A000. This scheme allows up to 24,999 user accounts: The accounts ending in 00 were group accounts, and the Z999 account held the login program.

HP TSB accounts

The System Master (A000) and all Group Masters (A100~Z900) are privileged users.

The System Master (A000) can save programs and files into the system Library.

Semi-privileged Users: User accounts beginning with the character A, specifically A000 through A999, can alter files sumultaneously.

Protected programs cannot be saved, punched or listed.

Semi-privileged Users with accounts ending with 00 can save programs and files into the group libraries.