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Computers & Calculators

This section encompasses arithmetic-logic systems of various types, including minicomputers, programmable logic controllers, electronic calculators and mechanical adding machines.

Felt & Tarrant Model J Comptometer

Comptometer-style mechanical calculators were once among the most common and popular forms of adding machine available. Though Felt & Tarrant originally invented and marketed the actual Comptometer brand calculating device, the word 'comptometer' has since become the vernacular. Comptometers are characterized by their massive array of keys. Unlike a modern calculator which only has a single set of numeric keys and forces the user to enter numbers one digit at a time, comptometers have a row of numeric keys for each digit. This allows a skilled operator to add numbers on the machine at a very fast pace, far faster than on a conventional calculator, by striking every row of keys at once. Comptometers are designed primarily for repetitive addition. Though capable of other mathematical operations, execution is not so straightforward. In fact, most of the entities that manufactured comptometer-style calculators ran academies which companies could send their employees to, in order to learn how to operate these machines. [View Detail]

Lightning Portable Adding Machine

The Lightning Portable Adding Machine is a device commonly referred to as an 'addometer', a popular type of calculator in the 1950s and 1960s due to their low cost and ease of use. Unlike complex comptometers and expensive 10-key calculators, addometer-style machines could be used by practically anyone, with little to no training. The controls of the machine consist of seven perforated wheels which resemble small rotary phone dials. Four of the dials are copper-colored; these dials are the cents and thousands indicators when working with currency. The perforations in the dials are marked with numbers. To perform addition, the user inserts a metal stylus into the appropriate hole and rotates the dials until the stylus catches the hook on the right side of the dial aperture. A small window above each dial displays the sum of the numbers entered into the unit, and a slide on the left side of the machine resets the display to zero. The unit is mounted in an angled bakelite stand for easy use, but is designed to be removed from the stand and placed directly on the document being added when performing long calculations. [View Detail]

Todd Protectograph Co. 'Star' Adding Machine

The Todd Protectograph 'Star' adding machine is quite small when compared to a comptometer from the same era, such as the Felt & Tarrant Model J. The front of the machine is bristling with ribbed sliders by which numbers are entered into the device. Each rib is labeled with a number mounted to an adjacent plate. To enter a number into the device, the user places their finger onto the appropriate rib and then pulls the slider down until their finger had pushed down the small button at the base of each slider. This is quite analogous to the operation of the digits dial on a rotary telephone. [View Detail]

Victor 6834 Adding Machine

The Victor 6834 uses a comptometer-style input system, with a row of sequential input keys for each digit. Although this machine is capable of displaying up to nine digits, only eight of then have input keys, as is normal for comptometers. The unit has no display; each number entered into the machine is printed on a standard roll of adding machine paper that is loaded into the back of the device. There is a mechanical accumulator suspended from the underside of the machine, and the lever to the right of the display is used to print and erase the contents of the accumulator. Subtraction is also possible by using the lever on the left side. Unlike many other comptometers from this era, the device has no motor. All mechanical power comes from pulling the lever on the side of the machine. [View Detail]

Burroughs C-3661 Programmable Calculator

The Burroughs C-3661 is a large, four-function programmable calculator with LSI logic and a transistor-driven Nixie display. The C-3661 is an improved revision of the C-3660, which is a slightly repackaged variant of the Sharp Compet 363P. Unlike the C-3660 and 363P, which both use the same Rockwell LSI chipset, the slightly newer C-3661 uses a Hitachi chipset. Programs are stored on magnetic cards, and internal memory is volatile. By far, the most striking aspect of this machine is its large display, constructed from 16 Hitachi Nixie tubes and two additional Hitachi display tubes. [View Detail]

Texas Instruments TI-2500 'Datamath' Calculator
	The TI-2500 'Datamath' is Texas Instruments' first production handheld calculator. Most variants of TI-2500 are built upon the TMS0119NC calculator chip, including this Version 1 example. [View Detail]

Texas Instruments TI-3500 Calculator
	Like the TI-2500, the Texas Instruments TI-3500 desktop calculator was introduced in September 1972. Along with the lower-cost TI-3000, the TI-3500 stands as the first desktop calculator to be produced by TI. The TI-3500 is built upon the TMS0106NC calculator chip, and features a 10-digit Panaplex display, produced by Burroughs. [View Detail]

Texas Instruments SR-10 Scientific Calculator
	The SR-10 is Texas Instruments' first scientific calculator, introduced in 1972. The model pictured here is the Version 2 variant, released in 1973. All variants of SR-10 are based on the TMS0120NC scientific calculator chip. [View Detail]

Texas Instruments 5TI

Devices included in this entry: Texas Instruments 5TI-1032-1 Sequencer Texas Instruments 5TI-2001 Programmer (pictured in thumbnail) The Texas Instruments 5TI is a compact TTL-driven programmable logic controller, designed for industrial automation. A basic system consists of a 5TI-1032 series sequencer, and a 5TI-2000 series programmer. The 5TI-2001 programmer is a handheld interface for the 5TI-1032-1 sequencer. It allows the operator to temporarily interface with the sequencer and enter program steps. This device does not have a power switch; it receives its power from the sequencer, through a permanently attached interface cable. The case of the 5TI is the same as that of the SR-20 scientific calculator, desktop companion of the SR-10 pictured above. However, its similarities to the SR-20 are superficial. The 5TI programmer is built from discrete TTL, implementing 39 TTL ICs in the programmer, and another 39 TTL, static RAM and UV-EPROM ICs in the sequencer itself. The display is a Burroughs Panaplex II with 10+2 digits, similar to the displays used in various TI desktop models from the same era. [View Detail]

Hewlett-Packard 2114B Computer

Devices included in this entry: 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. 2114B Brochure (PDF) 2114B Price Sheet 06/1970 (PDF) 2114B Price Sheet 05/1971 (PDF) 2114B Volume 1: Specifications and Basic Operation (PDF) 2114B Volume 2: Operation & Maintenance Manual (PDF) 2114B Volume 3: Input/Output System Operation (PDF) 12618A Synchronous Data Set Interface Kit (PDF) 2912A Reed Scanner 1969 Catalog Excerpt (PDF) [View Detail]

Hewlett-Packard 21MX / 1000 M-Series Computer

After the 2100A and 2100S, HP released the 21MX series, believed to be the industry's first minicomputers to be equipped with semiconductor RAM. The original 21MX series from 1974 consists of three models of ascending size and expansion capacity: 2105A, 2108A and 2112A. The 2108B (pictured here) and 2112B were added to the series in 1976, the most notable improvement over the 'A' variants being the relocation of the power switch from the rear of the CPU to a more traditional and accessible location behind the lockable front panel. In 1976, HP released the improved 21MX E-Series, renaming the original 21MX computers as 21MX M-Series to distinguish them from the E-Series systems. When HP released the third generation of 21MX systems in 1978, the naming convention was changed once again. These new systems were named 1000 F-Series, and the older 21MX systems were renamed as 1000 M-Series and 1000 E-Series to maintain conformity. 1000 M-Series Installation & Service Manual (PDF) [View Detail]

Reynolds & Reynolds VimNet

Devices included in this entry: Reynolds & Reynolds VimNet 9000 computer (pictured in thumbnail) Reynolds & Reynolds TC-1000 smart terminal (pictured in thumbnail) The VimNet 9000 is a specialized PDP-11 derivative minicomputer designed for auto dealerships. The system is built upon a Motorola 68020 microprocessor running at 16 MHz and is equipped with 4MB of RAM. A tape drive and bulky plexiglass hard drive provide secondary storage. The hard drives in these devices were originally only 140 MB, but the drive in this particular unit is marked with a sticker stating that it was serviced in 1991, suggesting a possible upgrade. This system was built sometime between 1979 and 1981. The most noteworthy feature of the VimNet is that it is gigantic. The VimNet server has connections for up to eight TC-1000 terminals. Even in the modest configuration shown here, with only a single Reynolds & Reynolds TC-1000 smart terminal, the combined weight of the entire system is at least 45 kg. It boggles the mind to think of an era when a car dealership would require such computing infrastructure. [View Detail]

Synertek Systems Corp. SYM-1

The SYM-1 is a single-board computer originally developed as a 6502 microprocessor evaluation board. The SYM-1 is an enhanced clone of the official MOS KIM-1 evaluation board, adding true RS232 and other improvements. The SYM-1 also shares the same I/O connectors as the Rockwell AIM-65, another 6502 evaluation system. SYM-1 Reference Manual 1/6 (PDF) SYM-1 Reference Manual 2/6 (PDF) SYM-1 Reference Manual 3/6 (PDF) SYM-1 Reference Manual 4/6 (PDF) SYM-1 Reference Manual 5/6 (PDF) SYM-1 Reference Manual 6/6 (PDF) SYM-1 BASIC Reference Manual (PDF) [View Detail]

GRiD PalmPAD 2351

The GRiD PalmPAD 2351 is a very early tablet computer that was designed for use by nurses and other people that needed to have a computer strapped to their arm at all times. The PalmPAD 2351 was manufactured in 1991, a full two years before the Apple Newton was released. The 2351 has no hard drive; a modified version of DOS is stored on a ROM, which permits it to boot without any configuration. The 2351 also has 2.5MB of battery-backed RAM, and a PC card slot allows the addition of hard drive space by means of flash memory PC cards. [View Detail]

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