page_title: HP 2100
section_title: First models
hierarchical_section_title: HP 2100 / History / First models
caption_attribution_description: English: HP 2115A Computer pictured without its power supply. This is object 20140927-0347 in The National Museum of Computing (www.tnmoc.org) collection.
context_page_description: The HP 2100 is a series of 16-bit minicomputers that were produced by Hewlett-Packard from the mid-1960s to early 1990s. Tens of thousands of machines in the series were sold over its twenty-five year lifetime, making HP the fourth largest minicomputer vendor during the 1970s.
  The design started at Data Systems Inc, and was originally known as the DSI-1000. HP purchased the company in 1964 and merged it into their Dymec division. The original model, the 2116A built using integrated circuits and magnetic-core memory, was released in 1966. Over the next four years, models A through C were released with different types of memory and expansion, and the 2115 and 2114 cost-reduced versions of the 2116. All of these models were replaced by the HP 2100 series in 1971, and then again as the 21MX series in 1974 when the magnetic-core memory was replaced with semiconductor memory.
  All of these models were also packaged as the HP 2000 series, combining a 2100-series machine with optional components in order to run the BASIC programming language in a multi-user time sharing fashion.
context_section_description: Led by Magleby, the new division completed the design as the 2116A, which was demonstrated 7–10 November 1966 at the Joint Computer Conference in San Francisco. It was one of the earliest 16-bit minis to hit the market, but is more notable as "an unusual new instrumentation computer" with a highly expandable design and real-time support. The system featured an oversized cabinet that held up to 16 expansion cards, or could be further expanded to 48 cards with an external expansion cage.
  The system launched with 20 different instrumentation cards, including "counters, nuclear scalers, electronic thermometers, digital voltmeters, ac/ohms converters, data amplifiers, and input scanners." An additional set added input/output devices like tape drives, printers, punched cards and paper tape and other peripherals. Real-time service was provided by having each card slot be assigned a fixed interrupt vector that called the appropriate device driver.
  As the machine entered the market, it quickly became clear it was selling much more rapidly into the business data processing market than the originally targeted instrumentation market. This led to the introduction of the 2115A in 1967, which removed much of the expansion capabilities to make a lower-cost offering for commercial users. A further simplified version shipped as the 2114A in 1968, which had only eight slots, leaving room for the power supply to be incorporated into the main chassis. The 2115 and 2114 also lacked the extensive DMA control of the 2116, removed some of the mathematical operations, and ran at slightly slower speeds.
  These are the original models using core memory and a hardwired CPU.
  2116A, 10 MHz clock, 1.6 microsecond (µs) cycle time. Normally supplied with 4k words, expandable to 8k internally or 16k with an external memory system. Chassis includes 16 I/O slots, also expandable. Weight 230 pounds (104 kg). Introduced November 1966. It marked HP's first use of integrated circuits.
  2116B, supported a new 32k memory expansion option. Weight as above. Introduced September 1968.
  2116C, used smaller core so a full 32k could fit in the main chassis. Introduced October 1970.
  2115A, short-lived cost-reduced version that removed the DMA and some math functions, had only 8 I/O slots, and ran at 8 MHz clock and a 2.0 µs cycle time. Weighed 65 pounds (29.5 kg), required a bulky external power supply — total weight: 160 pounds (72.6 kg). Introduced November 1967.
  2114A, further simplified 2115 with a new front panel and internal power supply. Non-mechanical touch switches on front panel. Weight 95 pounds (43.1 kg). Introduced October 1968.
  2114B, 2114A with a single DMA channel and a new front panel with illuminated push-buttons. Introduced November 1969.
  2114C, as 2114B with a maximum 16k memory. Introduced October 1970.
caption: HP 2115A Computer pictured without its power supply.
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