HP 2100 - Descendants and Variants

Descendants and Variants

The HP 9810, 9820 and 9830 desktop computers used a slow, serialized TTL version of the 2116 CPU, although they did not ultimately use any of the operating system or application software, instead relying on user-friendly ROM-based interpreters such as BASIC which worked when powered up and integrated keyboards and displays rather than disks or standard terminals. In 1975, HP introduced the BPC, the world's first 16-bit microprocessor, using HP's NMOS-II process. The BPC was usually packaged in a ceramic hybrid module with the EMC and IOC chips, which added extended math and I/O instructions. The hybrid was developed as the heart of the new 9825 desktop computer. The later 9845 workstation added an MMU chip. These were the forerunners of personal computers and technical workstations.

The major differences between the original 2116 architecture and the BPC microprocessor are a completely redesigned I/O structure, the removal of multiple levels of indirect addressing, and the provision of a stack register for subroutine call and return. The elimination of multiple indirection made an additional bit available in a memory word containing an indirect address, allowing the maximum memory capacity to be increased from 32K 16-bit words to 64K. The BPC also added an input allowing the "current page" to be relative to the location of the current instruction, rather than a power-of-two aligned page.

The BPC was used in a wide range of HP computers, peripherals, and test equipment, until it was discontinued in the late 1980s.

The HP 2100 is one of many 8 and 16 bit machine architectures said to be inspired by the PDP-8. These can be characterized by use of RAM instead of registers, and a small number of accumulators (such as A and B) rather than a relatively large number of regular registers (such as R0-R7 or R15) found on the PDP-11. This philosophy can save money when RAM is less expensive than registers.

Poland manufactured an HP 2114B clone since 1973. The Polish clones were called MKJ-28 (prototype, 1973), SMC-3 (pilot production, 17 machines, 1975-1977) and PRS-4 (production in series over 150 machines, 1978-1987).

Czechoslovakia produced its own HP 1000 compatible clones, designated ADT4000 (4300, 4500, 4700, 4900). More than 1000 units were delivered by the vendors Aritma Prague (development), ZPA Čakovice and ZPA Trutnov between 1973 and 1990. Those computers served in power plants, including nuclear ones, other industry, military, at universities, etc., for their high reliability and real-time features. Operating systems were DOS/ADT (several versions) and Unix. The oldest hybrid ADT7000 (1974) was composed of digital ADT4000 and analog ADT3000 parts, but only the digital part was interesting for customers. ADT4316 (1976) had 16K words of ferrite core memory, the ADT4500 (1978) up to 4M words of semiconductor RAM. The ADT 4900 was designed as a single-board computer, but its mass production did not start yet. Czechoslovak People's Army used ADT based MOMI 1 and MOMI 2 mobile minicomputers, built into a container carried by the Tatra 148 truck.