Hewlett-Packard 2114B Computer (pictured in thumbnail)
Hewlett-Packard 2912A Reed Scanner
Hewlett-Packard entered the computer business in 1966 with the HP 2116A, the industry's first commercially viable 16-bit minicomputer. Unlike most minicomputers, which were designed primarily for data processing, the 2116A was built from the ground up as a real-time instrument controller.
The 2116A and its earliest descendants (2116B/C, 2115A, 2114A/B) are hard-wired word-addressed 16-bit CPUs with discrete logic and core memory. The second generation of systems, the 2100A and 2100S, incorporate all of the capabilities of the most powerful first-generation systems, with the added benefits of microprogramming and a faster cycle time. The 2100A is noteworthy as being the industry's first microprogrammable minicomputer.
The early HP 2100 series computers are regarded
as some of the most reliable computers ever built; systems often
ran continuously for years without failure. They also marked the
birth of a CPU architecture that would be adapted and utilized
in numerous HP computers, calculators and analyzers over the next
two decades.
The Hewlett-Packard 2114B computer is a size-reduced, cost-reduced descendant of the original HP 2116 minicomputer. Released in 1969, the HP 2114B uses a 16-bit derivative PDP-8 architecture, as do all of HP's earliest systems. Its technology consists of SSI TTL integrated circuits and ferrite core memory.
In terms of engineering quality, the 2114B is the most refined of the early 2100 series models. The 2114B features a TTL chipset, DMA upgrade capability and wide temperature core option, none of which are features of the externally identical 2114A predecessor model. Additionally, the 2114B is the only early HP model to support 500kwps high speed input/output (HSIO), optimizing it for use as a dedicated I/O processor in a dual-CPU HP 2000 series system.
The main disadvantage of the 2114B is that the relatively small chassis constrains it to only seven I/O slots, the fewest of any early HP computer. Other features lacking in the 2114 are an extended arithmetic (hardware multiply/divide) option, and a slower memory cycle time: 2.0 usec versus 1.6 usec for the 2116. Perhaps the most unique and frequently noted feature of the 2114A/B is its illuminated proximity-sense
switches. In contrast, the 2116A/B/C and 2115A front panels have chrome toggle switches and illuminated pushbuttons, while later models feature illuminated pushbuttons (2100A/S) or pushbuttons with adjacent LED indicators, (21MX series).
The 2114B is HP's first and only all-TTL minicomputer. All other early systems (2116A/B/C, 2115A, 2114A) primarily use the Fairchild CTuL chipset. Additionally, the newer 2100A/S models use about 2/3 TTL, 1/3 CTuL. The 2114B only utilizes a small number of CTuL devices: three examples of Fairchild 9956 dual 2-in AND buffer, an insignificant fraction of the total IC count.
Hewlett-Packard 2114B Computer, short video of power-on and front panel operation.
2114B, internal details.
2114B, serial number 1105A-00726.
2114B, front panel illumination test.
2114B, protected controls concealed behind a lockable front panel.
2114B, top cover removed, showing the internal layout. Visible in this photo is the Ampex magnetic core memory, F/N 3255877-01 E S/N FA 106 (4,096 words).
2114B, closeup of the card cage.
2114B, hand-wired backplane.
2114B, left side cover removed.
2114B, right side cover removed.
2114B, closeup of core planes.
The 2114B featured in this exhibit was rescued from a
now-defunct manufacturing firm in 1996. The computer
is in excellent condition and is completely original except for
the LED retrofit and line switch replacement described below. Unfortunately, the front panel exhibits some intermittent defects, related to stress wear on the cable leading from the front panel to the CPU.
2006-03-22: Line switch failed and was replaced with identical OEM switch. Front panel retrofitted with four-die yellow LEDs (T-1 3/4 midget flanged, 24VDC, positive base).
2008-05-19: CPU upgraded with a 12618A Synchronous Data Set Interface Kit, card #12621-60001 (receive) and #12622-60001 (transmit).
2114B, Switch replacement and lamp retrofit.
2114B, Driver/Switch Card 02114-60427 (A1,2).
2114B, Inhibit Driver Card 02114-60429 (A3).
2114B, Memory Parity Check with Interrupt 12598-6001 (A5).
Copy of A Pocket Guide to HP Computers, originally owned by Homebrew Computer Club alumnus George Morrow (deceased). Computer engineers in Poland used a copy of this publication to construct the prototype MKJ-28 minicomputer, an exact functional clone of the HP 2114B. The subsequent SMC-3 and PRS-4 production models also have full logical conformity with the early 2100-series systems.
Pictured below is the HP 2912A, a scarce component of HP's first-generation data acquisition systems. It is a modular, expandable input scanner capable of switching up to 1000 channels (40 in mainframe) at up to 40 channels per second. The 2921A and 2922A plug-in modules each provide 10 channels, and the 2923A provides 9 channels. Though capable of independent operation, the 2912A was often controlled by a HP 2100 series computer.
The 2912A has flip-down front panel, revealing an array of 44 switches and two small pull-out boards with unusual repositionable diodes, which allow the user to program the 2912A. The front panel also has a 3-digit TTL-driven nixie display which indicates the current address, and six 10-position rotary switches to set the first and last address. The reed switch modules are flat, aluminum-encased packs, inserted into the back of the 2912A. They occupy the full internal height and depth of the chassis.
Hewlett-Packard 2912A Reed Scanner, serial number 910A00202.
2912A, concealed controls. Note the two diode plugboards beneath the bank of switches.
2912A, reconfigurable diode plugboard.
2912A, rear panel. This 2912A is equipped with Option 01 (computer interface?), 2921A Low-Level DC Module, 2922A DC AC Module, and a 2923A Frequency Module.
2912A, internal view.
Hewlett-Packard 2921A Low-Level DC Module.
Two-page advertisement featuring the 2005A Real Time Executive system, as designed by HP for Continental Testing Laboratories. The configuration pictured in the advertisement includes among other things, a 2116 computer, 2114 computer, and a 2912A Reed Scanner. It should be noted that the system pictured in the advertisement is very different from the 2005A configuration described in the 1970 HP catalog, which is a smaller single-CPU system.
