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Wang Model 362E Calculator

The Wang 362E was the last and most feature-packed machine in the Wang 300-series of calculators. The 362E represents the end of the line for the 300-series, as by the time it was introduced (March of 1968), calculators from competitors such as Hewlett Packard (an example being the HP 9100B) had eclipsed the 300-series in capability and speed. Wang had to come up with a new, cutting-edge calculator architecture quickly or risk losing large amounts of its lucrative market share to new competitors in the marketplace. HP's 9100-series calculators had many more features and capabilities than Wang's machines, were much faster, and were self-contained in a single desktop package, making them extremely desirable to customers looking for an advanced calculator. Wang Labs' had been caught somewhat by surprise by the actions of competitors. They had become a bit complacent, basking in the glow of the extraordinary success of the 300-series. The announcement of HP's new calculators, along with other forces in the market, forced the president of Wang Laboratories, Dr. An Wang, to make a quick decision. Wang Labs had been working on a project to develop a new business. Dr. Wang saw the meteroic success of Digital Equipment Corporation, and their brilliantly simple mini-computer, the PDP-8. A project had been initiated to build a computer that would beat Digital Equipment at their own game, and place Wang in a leadership position in the mini-computer market. However, because Wang's calculator business was the primary source for revenue for the company, and the competitors had very quickly begun taking away a serious chunk of the business, Dr. Wang's reaction was to do a hasty rework of the mini-computer project. The mini-computer design that had been developed thus far was modified to change it into a very powerful programmable calculator. This redirection of Wang's computer effort brought rise to the Wang 700-series calculators (for example, the Wang 720C), which was a very capable machine that allowed Wang to recapture some of its lost market share. The problem Wang had was timing. There was a period of time between the competitor's calculator introductions (and their almost immediate erosion of Wang's stranglehold on the high-end calculator market), and the time that Wang's 700-series machines were ready (mid-1970) for the marketplace. Something was needed to fill this gap, to stem the loss of sales to competing calculator makers.

Wang 362E Model/Serial Number Sticker

The earlier members of the 300-series, such as the Wang 360E, had fairly limited memory capacity, and their programming capabilities were rather primitive. A 300-series machine was needed that would allow Wang a little more fight out of the aging 300-series until the 700-series was ready. In order to provide better data-storage capabilities, the 300-series architecture was augmented to add more memory registers, as well as provide for direct memory register arithmetic. These fairly subtle changes to the 300-series architecture became the 362E, the interim calculator developed to fend off the competition while the 700-series was being developed. Wang's strategy was to convince the potential customer needing a more advanced calculator that a Wang 362E electronics package connected up to a Wang 370 or 380 "Programmer" would give them the basic features they needed, at a lower price than the competitors. Wang deeply discounted the prices on 300-series machines as part of this strategy to make the machines more attractive. To sweeten the deal, Wang would arrange a sizable credit to the customer for the trade-in of the 300-series system in exchange for a 700-series calculator once the 700-series machines were available. In some cases, Wang provided very inexpensive short-term leases on 300-series calculators to customers who were considering buying a competitor's calculator, just to get the deal and sell the customer a 700-series machine later.

Along with the fact that the 300-series calculator's capabilities were starting to become less of a selling point in the growing high-end calculator marketplace, another factor contributed to the competitive demise of the 300-series, the aging of the technology used to make them. The 300-series calculators were discrete transistor designs. There are no integrated circuits (also called "microcircuits") in these machines. At the time the 300-series calculators were designed (during the late part of the early 1960's), integrated circuits were simply too expensive. IC's were used primarily in military and computer applications where their cost was more easily handled by the needs of these demanding markets. Military weapons systems and large mainframe computers were markets that had lots of money behind them. During the height of the Cold War, military contractors needed to cram increasingly more sophisticated weapons electronics, radar systems, and avionics into very limited space, along with stringent weight and power specifications. The only way to meet the requirements was with integrated circuits. Large scale mainframe computers were required to be faster and more capable to handle the exponentially growing computing needs of large business and government. Computer manufacturers also had to resort to IC's, as the limits of transistor technology made building computers out of discrete components impractical. In the world of calculators, though, transistors were inexpensive and plentiful, were a well-known technology for the electronics engineers of the time, and, with the limited complexity of a calculator, were very practical for use as the mainstay implementation technology for a calculator. That is, until the late 1960's, when the cost of integrated circuits had began to come down. Japanese calculator manufacturers such as Casio(Casio 121/Commodore 1121, Sharp(Compet 16), and Hitachi(Singer/Friden EC1113), among others, had begun using small and medium-scale IC's in their calculators. The use of integrated circuits substantially reduced the size and cost of calculators, and increased the machines' capabilities and speed. This technology pressure also contributed to the end of development for the Wang 300-series calculators, as their all discrete component design meant that the machines were more complicated to build, took up more space, were less reliable, and used more electricity than the up and coming calculators from Japan that used integrated circuit technology. The 700-series calculators were designed using integrated circuits because a machine with such capabilities was simply way too impractical to build using the discrete-transistor technology of the 300-series calculators.

Warning Sticker - Not Good to Unplug the Keyboard/Display Unit with Power Applied

Like all of the other Wang 300-series calculators, the 362E system consists of an electronics package that contains all of the circuitry that performs the calculations, and a separate keyboard/display unit that plugs into the electronics package (which can be located up to 200 ft. away). From a functional perspective, the Wang 362E is identical to the Wang 360E and other members of the 300-series, with the exception of its additional memory register capabilities. As with all of the members of the 300-series, the 362E has a numerical capacity of 10 digits, with 14-digits maintained internally to provide more accurate results. All 300-series calculators operate with full-floating decimal point, and share a complement of four working registers; two accumulator registers (called the "Left" and "Right" adders), the "Working" register (where numbers are entered, and results placed), and the "Log" register.

The Log register, part of Wang's unique digital log/antilog generation circuitry, is used for performing multiplication and division, along with the square, square root, natural logarithm, and natural antilogarithm functions. This electronic logarithm generation circuitry is what gave Wang's first-generation LOCI calculators, and the 300-series machines the built-in scientific capabilities that bettered competitor's calculators and gave Wang Laboratories a dramatic lead in the high-end calculator marketplace from the late part of the early 1960's, though around 1968, when the competitors finally caught up.

Mechanical Assembly Quality Assurance Sticker (Located inside unit)

This particular 362E was mechanically assembled in late June of 1969, and received it's final pre-ship Quality Assurance inspection on May 30, 1970. It is clear that Wang inventoried mechanical assemblies (chassis/backplane/power supply), and a supply of Logicblocs. When a customer ordered a unit, the Logiblocs were installed in a waiting chassic, the assembly tested and given final inspection, and shipped. This is why the mechanical QA sticker (seen above) and the final QA sticker (unable to image due to fading) have different dates. The final QA sticker (usually located on the bottom of the electronics package right next to the model/serial number tag) should have a date that is later than the mechanical inspection tag (usually located inside the cabinet, on the backplane side of the chassis, near the power supply).

The distinguishing feature of the 362E is its extended memory functionality versus other memory-capable machines in the 300-series. The Wang 360E, 320SE, and 360SE calculators provide four independent store/recall memory registers. Each of the four registers may have a number deposited into them, or recalled. On these machines, a total of eight memory function keys provide access to the four memory registers, with each set of two keys providing a "STORE" and "RECALL" function for each of the four registers.

The 362K Keyboard Layout

The 362E marked a rather dramatic departure from the memory register architecture of the earlier 300-series machines, providing a total of 12 memory registers which also function as accumulators, as opposed to the 'store/recall' function of earlier machines. Because it would be impractical to provide individual keys on the keyboard unit to provide store/recall/add/subtract keys for each of the twelve memory registers (that would be 48 keys!), Wang opted to make memory access on the 362E a two step process, with the first keypress designating the memory function (store/recall/add/subtract) and the second keypress selecting which of the twelve memory registers the operation is to be performed upon. The memory registers on the 362E are numbered zero through eleven, with registers zero through nine addressed by a press of the corresponding key on the numeric keypad. Register ten is addressed by pressing the "CLEAR DISPLAY" key, and register eleven is addressed by pressing the "CHANGE SIGN" key. So, for example, to recall memory register ten to the display, the "RECALL FULL" (more on why the "FULL" designation is included later) key would be pressed to indicate to the machine that a recall operation is to be peformed, and then the "CLEAR DISPLAY" key would be pressed to indicate memory register ten is the register whose contents should be recalled to the display.

To provide even more capability to the memory function of the 362E, Wang added the ability to divide each memory register into two half-registers, allowing up to 24 numbers (of reduced magnitude) to be stored in the memory system. The capability to store up to 24 numbers allowed the 362E to be able to perform small matrix manipulation operations -- an important feature for tasks such as solving systems of simultaneous linear equations and statistics operations. How this half-register function works requires a bit of digging into the general register storage architecture of the 300-series calculators.

Silk-Screened "Brag Tag" Proudly Adorning the Top Surface of the 362E Electronics Package

As mentioned earlier, the Wang 300-series calculators all use small-capacity magnetic core memory arrays to provide the storage for the operating registers of the machine (Left Accumulator, Right Accumulator, Logarithm Register, and memory registers on machines so-equipped). Also mentioned earlier, each register contains fourteen digits, with ten digits represented to the user on the display, and four 'hidden' digits used to increase the accuracy of scientific functions. Along with the fourteen digits in each register, it is necessary to keep track of two more pieces of information for each number stored in a register -- the location of the decimal point, and the sign of the number. In the Wang 300-series calculators, an additional digit position is used to indicate the decimal point location, and the sign of the number. This means that each register consists of sixteen decimal digits. The 300-series calculators represent decimal digits in Binary-Coded Decimal form, where the digits zero through nine are represented by their binary representation (e.g., 0=0000, 1=0001, 2=0010, 3=0011, ..., 9=1001). It takes four bits to represent each decimal digit, so a total of 64 bits comprise a register in the core memory of the 300-series machines. As an example, to represent the number "+123.456", the internal represetnation would contain the fourteen digits "12345600000000", along with two additional digits to define the decimal point location (3) and the sign of the number (0).

The decimal point location is represented by the number of digit positions the decimal is located within the number from the left-most digit position, beginning with zero representing the decimal point being located before the left-most digit. In the example above, this would be '3'. In the number "6.23", the decimal point location would be '1', and for "23456.12", the decimal point representation would be '5'. The sign of the number is represented by a digit of "0000" if the number is positive, and "1111" if the number is negative. Back to our example of +123.456, we end up with

 0000 0001 0010 0011 0100 0101 0110 0000 0000 0000 0000 0000 0000 0000 0000 0011
  +    1    2    3    4    5    6    0    0    0    0    0    0    0    0    3
|SIGN| -------------------------  N U M B E R ---------------------------- |DEC |
being stored into the 64-bit core memory location. The first 56 bits represent the number itself ("12345600000000"), the next four bits are the decimal point location, and the last four bits are the sign indication.

Now that the method of storage of numbers in the calculator is understood, it is possible to explain the concept of dividing the twelve full memory registers in half to provide 24 'half-sized' registers. Each half-register consists of 32 bits, 24 of which store the number itself, four bits representing the decimal point location within the number, and four bits representing the sign. Using this means, each 'half' register can store a number in the range of -999999 to +999999. The halves are referred to as the "A" and "B" halves of each register. For example, the "A" half of register eight could store the number "254.3", and the "B" half could have "-1086.55". This would be represented the 64 bits of storage register eight as follows:

 0000 0010 0101 0100 0011 0000 0000 0011 | 1111 0001 0000 1000 0110 0101 0101 0100
  +    2    5    4    3    0    0    3   |  -    1    0    8    6    5    5    4
|SIGN| ------ A   H A L F -------- |DEC  | SIGN| ------- B   H A L F ------- |DEC |
Given this organization, a total of eight memory function keys (the same number used on the earlier calculators with memory functionality) can control the operation of the memory on the 362E. The eight memory functions are "STORE FULL" and "RECALL FULL" (which store or recall a full memory register), "ADD FULL" and "SUB FULL" (which add or subtract the number in the display to the selected full memory register), "STORE HA" and "STORE HB", which store the number currently in the display (truncated to the most significant six digits) into the "A" or "B" half of the selected memory register, and lastly, "RECALL HA" and "RECALL HB" which recall the A or B portion of the selected memory register to the display. The beauty of this design is that existing Wang 300-series keyboard units with memory function keys can be used on the 362E by simply changing the keycap nomenclature on the eight memory function control keys to indiciate the 362E's memory functions. The Wang 360K and 360KT/KT keyboard/display units can be used on the early 300-series memory-capable electronics packages (360E, 320SE, 360SE), or on the 362E by simply changing the paper keycap labels. This design meant that Wang could re-use these keyboard units with no changes other than making new paper legends for the keycaps. This rather elegant enhanced memory architecture helped keep costs of the 362E down, as Wang didn't have to design new keyboard/display units to work with the different memory architecture of the 362E. In fact, once the 362E was introduced, Wang changed the model numbers of the 360K, 360KT and 360KR keyboard/display units to 360/362K, 360/362KT, an 360/362KR. Another benefit was that Wang's programmer units (the 370 and 380) were also compatible with the 362E (again, needing only paper keycap nomenclature changes for the memory function keys), allowing the 362E electronics package to serve as the core for a more-capable programmble calculating system.

The Wang 362E electronics package shares a similar mechanical design to that of the Wang 360E. The electronics package consists of briefcase-sized sheet-aluminum package with an attached power cord, and a connector for plugging in the keyboard/display unit. A metal carrying handle allows easier transport of the relatively heavy electronics package, which weighs about 20 pounds.

The electronics package consists of four main assemblies. The first is the chassis/cabinet, which is made of heavy gauge stamped aluminum. The cabinet consists of three main components, the chassis itself, serving as the foundation for the electronics, and two covers, each of which are secured to either side of the chassis by two screws each. The covers provide protection for the backplane and the circuit boards.

The Power Supply Circuit Board

The next assembly is the power supply, which consists of a fairly large transformer mounted separately, which connects to a printed circuit board that contains the rest of the power supply electronics. The power supply is a linear design, using discrete power diodes for rectification of the AC power coming from the transformer, large computer-grade electrolytic capacitors as ripple filters, and simple resistive setpoints for the logic supplies, which are +11 and -11 volts DC relative to ground. Another section of the power supply generates approximately 250V to drive the Nixie tube display in the keyboard/display unit.

The Backplane of the Wang 362E

The third major part of the electronics package is the backplane. It seems that Wang Labs was very comfortable with point-to-point wiring technology for many of the 300-series calculators. The backplane of the calculator consists of a collection of 30-pin edge connectors, two for each circuit board (for a total of up to 60 connections to each Logibloc) that have long rectangular-shaped wire tails to which individual wires are connected (via an interesting clip technology that both provides a mechanical connection as well as a secure electrical connection) to provide the interconnections between the various circuit boards that plug into the backplane.

Closer View of Backplane "Clip" Interconnect Technology

Some Wang calculators, such as the 360E exhibited in the museum, used a printed circuit board backplane, but the vast majority of Wang's machines seem to use the tried-and-true point-to-point wired technology. It appears that toward the very end of 300-series production, Wang switched over to printed-circuit backplanes as another cost-cutting measure to keep their aging machines as competitive as possible.

The Logiblocs that make up the Logic of the Wang 362E

Lastly, the electronics package contains the "Logiblocs" (as Wang called their circuit boards) that contain the circuitry of the calculator. There are 26 circuit boards, each of which contains various sections of the calculator logic. Each fiberglass circuit board measures approximately 6 1/4" by 3 3/4", and has printed circuit wiring on both sides of the board. The front side of each board contains the transistors (most of which are made by RCA), diodes, and various passive components that implement the logic, as well as interconnecting traces. The back side of the Logiblocs contains only interconnection traces. Connections between the front and back sides of the boards are made by traditional feed-through holes, which are plated through the board to allow an electrical path through the hole. Each board has two xx-pin groupings of edge-connector fingers to plug into the backplane. The edge-connector fingers are tin-plated, which, while inexpensive, is not nearly as reliable as gold-plated edge connector fingers. The tin fingers tend to corrode, which causes excessive resistance in the connection between the board edge finger and the connector the board plugs into. This corrosion is the most common form of failure in the Wang 300-series calculators. Simply cleaning the fingers with the appropriate contact cleaning solution or, in lieu of that, a simple pencil eraser, can be the source for fixes a great many of the problems that a malfunctioning machine may have.

The 362E benefits from design reuse from earlier machines in the 300-series. In fact, of the 26 circuit boards in the 362E, 20 boards are identical to and interchangeable with those used in the 360E. The core memory board in the 362E the same as used in Wang's earlier 320SE electronics package, leaving only 3 boards that are unique to the 362E. These three boards implement the unique memory functions of the 362E. This efficient reuse of earlier designs allowed a quick design time on the 362E, easier manufacturing, and little in the way of additional training needed for service technicians, making the 362E an economical "bridge" machine to keep Wang competitive in the marketplace as the 300-series aged. However, while the 300-series architecture was flexible enough to allow such hacks, the 362E represented the limits to which the architecture could be stretched without major re-design.

The logic of the 300-series calculator is all hard-wired, meaning that the sequential logic that carries out calculations is guided by various logic devices wired specifically together to perform given functions. The fact that the 300-series calculators had hard-wired logic was another reason why Wang had to scramble to come up with the 700-series to replace the 300-series. Hewlett Packard used a microcoded architecture on their HP 9100 calculators. A microcoded architecture uses a read-only memory (ROM) to store micro-instructions that guide the calculator through the logical steps of solving a problem. Microcoded logic architectures were originally developed for large computers, to allow flexibility in the design of the machines. The principle was applied to calculators, because by simply changing the microprogram in ROM, the function and features of the calculator can changed without having to re-wire the basic logic of the calculator. Hewlett Packard leveraged a microcoded architecture in their amazing debut electronic calculator, the HP 9100A. The introduction of this machine was the trigger that sent Wang Laboratories into a panic to build a next-generation replacement for the 300-series. Shortly after HP introduced the 9100A, HP's engineers developed some minor microcode changes (along with a few minor hardware changes), and introduced the 9100B, which doubled the data and program memory capacity of the 9100A, and added additional subroutine capabilities. The flexible microcoded architecture used in the design of these machines allowed HP to make relatively minor changes to the architecture of their calculator, and produce a new model in a very short time that added significant functionality, without having to change the fundamental architecture of the calculator. The hard-wired logic of the 300-series calculators made feature changes significantly more difficult. This, along with the other limitations of the 300-seriers calculators, was a reason why the 362E was the end of the line for the 300-series calculators -- the hard-wired architecture had simply evolved to the point where any significant feature changes beyond those made for the 362E would essentially require a whole new design. This is why Wang chose a microcoded architecture for the 700-series calculators, in hopes that such an architecture would allow on-going updates to the features and capabilities of the calculators as time went on. As it turned out, Wang's choice to go with a microcoded architecture was the right one, as the 700-series design evolved into follow-on machines including the Wang 600-series and 500-series calculators which carried Wang's calculator business well into the 1970's without significant architectural changes.

The "541" Core Memory Board Used in the 362E (Sense amplifiers on left, Inhibit Drivers on Right)

The logic of the 362E (like the other members of the 300-series) centers around the core memory subsystem, since all of the working registers of the calculator are stored there. A series of binary counters with decoded outputs form sequencers that direct the overall operation of the calculator. The logic is constantly cycling through the core memory, sequentially reading the content of the W (Working) register and displaying it on the Nixie tube display. At the same time, the logic is looking for keypresses on the keyboard. When a key is pressed, the logic of the machine 'shifts gears', continuing the display process, but also performing other logical operations to carry out the operation specified by the keypress. The core memory system contains a total of sixteen 64-bit registers, four of which contain the working registers of the calculator (W, L, Left Accumulator, Right Accumulator), and the other twelve containing the memory storage registers. The core array, which is arranged in four planes of 16 by 16 bits each, resides on a single circuit board, along with four sense amplifiers and four inhibit drivers. The row and column addressing circuitry for the core array exists on four other circuit boards, with each board driving eight rows or columns of the core array. Lastly, one more board contains (among other things) the constant-current source that provides the current used by the row, column, and inhibit drivers.

As with the other members of the 300-series, the 362E allows a Wang CP-1 or CP-2 Card Programmer to be connected in series with the keyboard/display unit to provide simple programmability. Other Wang 300 peripherals, including the IC-1 Item Counter, also will operate with the 362E. The Wang 370 and 380 Programmer keyboard/display units also operate with the 362E. These keyboard/display provide more complete programming functions, including test and branch capabilities, and I/O control. The programmers also provide interface to a wide range of peripheral capability, including printers, additional external core memory storage, Teletype interface, and much more.

The Wang 300-series was the true beginning of Wang's early dominance of the high-end electronic calculator market. Wang's first calculator, the LOCI, was a bit tedious to use, and while it got Wang Labs into the calculator business, the refinements made to the 300-series calculators were the key that truly launched Wang into a lead role in the market, generating countless millions worth of sales during their lifetime, which spanned from 1965 through around 1973. While sales of the 300-series machines continued into the mid-1970's, active development of the line had ended by mid-1969. Back in those days, it wasn't unusual for a manufacturer's calculator model to be replaced by a newer, better machine in 12 to 18 months. The usable lifetime of the 300-series calculators was truly amazing. The 362E may have been the last of it's kind, but the longegity of it and the other members of the 300-series family was a great testimony to the ingenuity of Wang Laboratories.

For more information on the operation and history of Wang 300-series calculators, check out the Spec Sheet for the 362E, which has links other 300-series calculators exhibited in the museum.


Text and images Copyright ©1997-2011, Rick Bensene.