Core Memories  
Written by Accutron on 2013-06-08  

For a list of all known 2116 / 2115 / 2114 machines, please refer to the Hewlett-Packard First Generation Computer Census.

For technical details on the 2114B computer, please refer to the Hewlett-Packard 2114B exhibit in our electronics museum.

HP entered the computer business in 1966 with the HP 2116A, the industry's first commercially viable 16-bit minicomputer. The 2116A began as machine called the DSI 1000, a 12-bit system designed by Data Systems Inc., a division of Union Carbide. HP bought DSI and the DSI 1000 design in 1964; four of the five DSI team members, along with a number of HP employees, formed HP's new computer division.

After substantially redesigning the DSI 1000 to fit HP's needs, the 2116A was born. Unlike most minicomputers, which were designed primarily for data processing, the 2116A was built from the ground up as a much-needed real time instrument controller for HP's fast-growing automated test equipment market. HP would later release two more iterations of the 2116, the 2116B and 2116C, each with a doubling of the maximum amount of available in-mainframe core memory from the previous iteration, from 8K to 16K to 32K.

Despite HP's intentions, the 2116A saw extensive use in data processing. This market pressure prompted HP to release the 2115A, a scaled down 2116A with an 8 MHz clock (versus a 10 MHz clock in the 2116A), eight I/O card slots instead of 16, and a large 2161A external power supply.

Further refinement of the scaled-down design resulted in the 2114A, a machine approximately the same size as the 2115A CPU, but with an internal power supply and a redesigned front panel. Despite its much smaller overall size, the 2114A has the same number of I/O slots as the 2115A, the same clock rate, and the same maximum memory capacity of 8K. Perhaps the most unique and frequently noted feature of the 2114A is its illuminated proximity-sense switches, likely the first example of a computer with a touch interface of any kind. In contrast, the 2116A/B/C and 2115A front panels have more conventional chrome toggle switches and illuminated pushbuttons, while later models feature illuminated pushbuttons (2100A/S) or plastic rocker switches with adjacent LED indicators (21MX series). The main drawback of the 2114A as compared to the 2115A is the lack of support for an extended arithmetic (hardware multiply/divide) option, and a reduced front panel readout. While the 2116 and 2115A systems have five register displays (T, P, M, A and B), the 2114A has only two register displays (T and M).

Following the 2114A, HP introduced the improved 2114B, the most refined of the early 2100-series models. Though externally identical to the 2114A, the 2114B features a TTL chipset, DMA upgrade capability and wide temperature core option, none of which are features of any other early model of HP minicomputer. The 2114B is HP's first and only all-TTL minicomputer. All other early systems primarily use the comparatively unreliable Fairchild CTuL chipset. Even the newer 2100A/S models use about 2/3 TTL, 1/3 CTuL. The 2114B only utilizes a small number of CTuL and DTL devices. Additionally, the 2114B is the only early 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 and DMA option availability constrains it to only seven I/O slots, the fewest of any early HP computer. Like the 2114A, the 2114B lacks support for an extended arithmetic option.

Although the 2114B was the final model of 2114 to enter production, HP did advertise and build at least one prototype model 2114C. The 2114C was nearly identical to the 2114B, but sacrificed one more I/O slot in favor of a maximum 16K of core memory. The only known prototype of the 2114C is currently being held hostage in some dark corner of the Computer History Museum.

This remainder of this article is a photographic history of early HP minicomputers, as told by Measure, the HP employee magazine. All photos are presented with their original captions, some slightly edited for context.


Computer engineering group includes, from left: Bob Gray, memory; Roy Clay, programming; Gene Stinson, logic; Kay Magleby, computer engineering manager; John Koudela, applications (standing); Ed Holland, logic; Dick Reyna, input/output.

Backplane of computer is automatically wired by tape-controlled machine which makes some 4,000 wire connections for over 500 different circuits in 3 1/2 hours, saving days of tedious and highly complex hand wiring. Bob Hoshi is operator.

Production models of the 2116A are tested near end of manufacturing line. At rear, Computer Production Supervisor Dave Weibel confers with Engineer Harlan Andrews. In foreground, Test Supervisor Larry Dassow checks with Test Technician Tony Hunt.

Donated by HP to Stanford University, this 2116A is used by the school's computer science department. Admiring gift, from left, Dr. John Herriot, department's acting executive head, and Dr. William McKeeman, faculty coordinator, with HP's W. F. Cavier, vice president and secretary.

Dymec computer in background figures in project involving the application of computer technology to problems of chemical analysis. Here, Irme Radvany reviews programming.


Research vessel Chain, out of Woods Hole Institute of Oceanography, offloads HP 2116A computer after recent voyage to measure interacting ocean influences. The computer fared well in its seagoing laboratory.

Loveland Division designed a special system, built around the HP 2116A computer, to test the [HP 9100] calculator's printed circuit boards. Ed Miller is shown with the system, which simulates the calculator's operation and provides test results, locates any faulty components, and prints the information on a teletype.

Pete Dawson (right) of Palo Alto Division describes a portion of the inner workings of the new 2012B data acquisition system for a prospective customer.

Components can be prime source of after-sale trouble, particularly when exposed to loads not contemplated in specs. Here, Microwave's Terry Bowman conducts computer-based test of parameters of transistor seen in foreground.


Checking out a software program - "debugging" - is an important phase for the programmers. John Wolff observes as an HP 2116B computer handles one of Palo Alto Division's new Real-Time Executive programs. Such software programs are becoming increasingly important HP products.

The HP 9500A automatic test system, demonstrated for visiting customers here by Dawson Mabey, is Systems Division's new and versatile entry into fast-growing systems market. The 9500A employs a wide range of standard and optional HP instruments.

Cupertino Division will concentrate on production of computer products such as 2100 family of processors shown here, along with supporting instruments and software. Checking shipping tag is Wes Brooks. Cupertino facility will be joint headquarters for the division headed by Tom Perkins as well as Data Products Group. Data Products' strategy envisions close liaison with divisions outside the group because of the strong marketing relationship of such products as the Loveland calculators, new plotters from San Diego, terminals from New Jersey, and CRTs from Colorado Springs.

Aircraft violating noise-limit regulations at Stuttgart stand very little chance of escaping detection by the HP Noise Monitoring System installed there recently. The system, first of its kind, features seven terminals positioned around the airport to pick up all takeoff signals and transmit them to the central station shown here. When reference levels are exceeded, the computerized central station logs all pertinent data. [...] Control tower operators can make use of system to direct corrective action while flight is still in progress or use tape for later study. The central station here consists of an HP scanner, spectrum analyzer, counter, computer, paper-tape reader, high-speed punch, and teletype.

HP's advanced measurement capability was essential in getting microcircuitry off the ground. Automated testing systems had to be devised both for in-process materials and finished devices. Here Karen Morano tests amplifier substrates.

FLIP, the Floating Instrument Platform launched by Scripps Institution of Oceanography in 1962, is either 355 feet long - or high. The latter occurs when the skipper orders the ballast tanks filled. This tips FLIP on end where she becomes steady as a fencepost even in raging storms - an essential condition of the acoustical research done. It also turns the recently installed HP 2005A real-time executive system right side up. The Scripps oceanographers told Neely engineers that the HP system, which was taken aboard in March to control FLIP's acoustical experiments, was selected because of its reliability under rugged conditions at sea. Actually, the system doesn't care which side is up; it will perform standing on its head if necessary.


Fundamentals of computer software are reviewed for HP directors and various Data Products Group hosts by John Pavone of Data Center at Cupertino plant.

Taking a look at final testing of a 2114A computer by Skip Norman are Tom Pike and Bill Hewlett. At rear is host division manager Tom Perkins.

The insides of an HP computer nearing end of production line are shown to Frank Cavier, Ed Littlefield and George Bennett by tour guide Frank Myers.

More than 100,000 decisions a second are made by this HP 2060A logic module test system in determining whether a printed circuit off the Cupertino Division production line matches up in performance to a similar circuit known to be functioning properly. The comparator system, operated here by lead technician George Simpson, not only tells if a circuit is sick but also what its specific ailment is. The result is that Cupertino now can test and repair as many as 8,000 very complex boards each month - an impractical task with this volume by methods formerly available.

Testing of conventional electronic instruments - faster and with greater reliability - is the goal of this system under development at Loveland Division. In addition, the system - still very much under wraps - is expected to meet definite customer needs outside Loveland and the company. Here, Art Minich (left) and fellow engineers at Loveland check a program. Not all instruments really lend themselves to computerized testing. But it becomes increasingly easier and more economical once hardware has been installed and software programming experience is gained.

There are plenty of signs that educators think highly of Hewlett-Packard computer-based educational systems. But this one's a landmark: In the Southern Regional Education Board's "three-year experiment on utilizing mini and very small computers for instructional uses;' five out of the ten participating small colleges chose HP equipment. Included are 2007's, disc-operating systems, and a 2000A for schools in South Carolina, Illinois, Tennessee and Ohio. Funding is being provided by the National Science Foundation.


For months Lee Frank, of the King of Prussia sales office, tried various approaches to selling: two-week seminars on computer programming as shown in photo above; one-day classes for math students; and a "computer caravan" that attracted teachers and staffs to seven locations in seven days on the road. Each had its success, but the caravan seemed most efficient. Orders for 2007A systems came in from three high schools. Finally, the Instructional Systems Division of Philadelphia called for a review of HP's new 2000B time-share system as a possible replacement for the system they had used in the past. When the order came in for the $100,000-plus system, Lee Frank and the other data products people concerned saw it as a good omen as well as a good sale.

A lot of owners of stand-alone HP computers are going to be made aware very soon of a nifty bonus situation: by spending as little as $10 for software, and by leasing extra teletype terminals at about $50 a month each, they've got themselves a mini-timesharing system. Up to eight terminals can be operated simultaneously. Most likely beneficiaries will be high schools, colleges and universities who have limited funds but a growing need to serve more students. Classes in math and beginning computer programming will find the mini-timesharing particularly useful. Actually, two new software packages are available. One, developed by programmers at Montana State University, accommodates up to four terminals. The other, from Pacific Union College at Angwin, California, will go to eight terminals. Compared with full-scale timeshare computer installations, prices for complete versions of each mini-timeshare system are about five times less. That should make good reading down at the local school board.

The age of the mini-computer in education moves apace with the completion of a program evaluating the HP 2007A Educational Computer System in a dozen Edinburgh-area schoois. The program, sponsored by the Moray House College of Education, sought to test the ability of whole rooms of students to learn the programming and operation of a computer under instruction of only one teacher. In the photograph are seen pupils at Ainslie Park Comprehensive School feeding into the computer the mark-sense cards they have programmed with an ordinary lead pencil at their desks.

Although HP products always have been designed to very high safety standards, the company has participated only to a limited extent in such code-setting and monitoring groups as Underwriters' Laboratories. Now, however, more and more customers need UL listing for the electronic products they sell to cities and other agencies that insist on conformity. The company is responding to this situation by a program having the eventual aim of company-wide participation. The new 7970B digital tape transport now in full production at Mountain View is the first of HP's data products to be granted recognition under the component program of Underwriters' Laboratories. According to Jim Gillette, QA manager who is presently responsible for monitoring the Mountain View program, the recognition process turned out to involve much less effort and expense than expected, because it was part of the design team thinking from the start. Doug Hanson, digital tape product manager, said that UL "recognition" is particularly important to OEM customers who plan to incorporate such products as part of their end-user systems. In turn, it is then easier for the OEM to obtain UL "approval", providing no significant modifications are made to the various recognized OEM components. Pictured in this view of the 7970 production line are, from left: Mike Byrne, Gary Bullen, and Vic Hanson.

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