First-Hand:PDP-8/E OMNIBUS Ride

contributed by Remo J. Vogelsang, Life Member, employed by minicomputer pioneer Digital Equipment Corporation [short form DEC], Maynard, Mass., U.S.A. from 1968 to 1972

Please click Smiley^{'s [index]} to get to some background information or maybe a funny tale ! Then click ↑ to return.

The Highlight

1970 - WESCON exhibition Western Electronic Show and Convention, Los Angeles, August 25-28

A London double-deck "digital PDP-8/E OMNIBUS^TM" toy - one of the 10'000 - helping to promote the new product at the 1970-WESCON show in Los Angeles. The author dug out this souvenir from one of his kid's play-bin he found in his attic.

I got dropped off the double-deck bus which had picked me up at the hotel that morning. The friendly hostess, dressed in matching red, said good-bye, and here I was right in front of the exhibition hall. Enjoying the morning rays of the August sun, I proudly glanced back at this red London double-deck bus with its "digital PDP-8/E OMNIBUS^TM" label posted between the two window rows across the giant vehicle (a fitting promotional effort for the novel PDP-8/E minicomputer's I/O bus). Inside at the DEC booth I was struck. A crowd of interested visitors and arguing sales people circled the prominently placed PDP-8/E with its rattling Teletype printer leisurely churning out plots. ^plot Next to it was a huge heap of piled-up Small Computer Handbooks, and then there was this big basket filled with red double-deck OMNIBUS toys as take-away gifts for the kids at home. With fascination and great satisfaction I kept watching visitors picking a couple of the OMNIBUS toys, then one or two of the handbooks from the pile and browsing in them before leaving the booth.

What an outstanding in-depth campaign to prove the PDP-8/E's distinguished new qualities. It also made visitors feel being most welcomed customers. I liked very much what I saw. And I was impressed by the fine job they had done, the people from public relations, marketing, sales, documentation. Having been permanently immersed in my engineering tasks and duties during the last months, I was not aware - until now - of all the preparations going on behind the scenes for a successful introduction of this product. As a prelude, they also had organized a PDP-8/E promotion for selected customers of the Bay Area, which took place at the Holiday Inn in San Francisco the week before.

The Beginning of a Long Journey

Education and Work in Switzerland

Born into a large family located in a small town in the German speaking part of Switzerland, I was fascinated by electricity as early in my life as I can remember. Any electrical installation I could spot would immediately draw my fullest attention. So from the moment I was told, that these things were done by electrical engineers, I wanted to become one of them.

Our father was a master mason, owning a small building company. Already as a first-grader, I studied all available blueprints at the construction sites and compared the building's progression against them. Any difference in detail I could spot, I would point to the crew, what they actually appreciated. To nobody's surprise, machines of any kind were also not safe from my explorer's delight.

Apprenticeship     At about fifteen, one had to decide which track to take for further education. With undisputed good performance at school, I was expected to choose an academic path. Moreover, I could count on the full support of my parents. Actually, this was what I wanted to do, although with a detour. I first wanted to get to know things, then accrue the skills to make them, and finally study to acquire the know-how to be able to create them. Against the recommendation of all my teachers and other people, I applied for an apprenticeship at Brown, Boveri & Cie (BBC) (since the merger with ASEA from Sweden in 1987 named ABB). Brown Boveri was a traditional Swiss electrical engineering company and with about 12'000 employees of impressing size and power. They sold worldwide well-known equipment and services for electrical power generation and distribution (including vapor turbines and gas turbines), as well as plant engineering for industries. An apprenticeship, lasting four years, is 'learning by doing' in a real company, supplemented by trade-related, focused studying in school - sort of an extensive work-study program. The majority of Swiss youngsters choose this track as the starting step of their professional career. In this model, craft and industry profit from a young, well educated workforce. For the country's economy it's a blessing, because this leads to very high employment of young people. At Brown Boveri, an apprentice was scheduled to change his workplace every half year within the company. This enabled him to gain insight and expertise in many different fields. The first half year was set up as an introductory course, organized in groups of sixteen apprentices for basic training in elementary metalworker skills. During the following years, the apprentices formed a close fellowship of teenagers spread across the vast company. On the one hand they carried quite a workload with responsibility at modest pay; on the other they were granted some fool's privileges as a balance. It was a place to grow-up.

Studies in Electrical Engineering     After successfully graduating from the apprenticeship program at Brown Boveri and after a two-year curriculum at a private school to attain the general qualification for university admission ('Matura') in 1959, I began my studies in electrical engineering at the Swiss Federal Institute of Technology in Zurich ETHZ. An excellent European university, hardly known in the US at that time, today is ranked as the best university in continental Europe. My preference was the electronics curriculum. Although profiting from a set of excellently lectured courses, semiconductor applications and digital circuit design were not yet among them. I enlisted in some voluntary up-to-date subject courses available at that time such as 'Transistor and active circuits' lectured by John G. Linvill from Stanford University during his sabbatical year in Switzerland, Halbleiterbauelemente lectured by Walter Guggenbühl and Digitale Rechenanlagen lectured by Prof. Ambros P. Speiser who founded and managed the IBM Zurich Research Center, the first research facility of IBM outside the US. My thesis partner and I had to develop the circuitry for a Tunnel-diode mixer as an experimental tool. The obtained results could then be compared with theoretical behavior. ^mixer Besides filter design, the challenging part of our task was to maintain stable operating conditions with the uncommon negative resistance property of the device, requiring a circuit layout conforming to gigahertz-frequency techniques, under the constraint of very limited availability of adequate instrumentation. This work was done within the department of 'Höhere Elektrotechnik' headed by Professor Max J. O. Strutt under the supervision of Hans Melchior. At the end of 1963 I graduated as 'Diplomingenieur (Elektroingenieur ETH)'.

My first Job as Development Engineer     I very much value my first job as a development engineer from 1964 through 1968 at the Oerlikon Bührle Company. My supervisor, a competent and experienced man, had - for good reasons - an affinity to US electronics. Books such as Radio Engineering , simply called the 'Terman' not knowing yet of his role in supporting the Varian brothers or Bill Hewlett and Dave Packard to start their companies and setting up the Stanford Industrial Park, then the Reference Data for Radio Engineers nicknamed the 'bible', belonged to our arsenal, together with a number of pertinent US magazines. Besides, most electronic parts used in our products were of US origin. We also had efficient access to any new semiconductor part of interest, which showed up in the US market at that time.

An extensive range of applications from low-level/low-noise IR detection, charge amplifier design, magnetic sensing, 20MHz counters for velocity measurements (still done with discrete transistors), to servo-control systems, opened up a versatile engineering field for a novice. Starting with a technology of discrete semiconductors (even with germanium, before silicon took over) and proceeding in using small-scale (SSI) and medium-scale (MSI) integrated circuits, allowed us to stay ahead of the crowd. Besides, the equipment we built had to withstand harsh environmental conditions, most notably an operating temperature range from -55°C to 70°C and vibration-sustainability according to standards like MIL-STD-810A. Generally the name of the game was "design products based on straight-forward solutions and simple handling; apply unconventional methods to reach the goals if useful". Here an example of the latter: In order to cut costs and save time on the expensive use of vibration tables before the actual validation could take place, we shipped prototype equipment from Zurich to Amsterdam and back by rail. Unpacking the freight would instantly tell even to a novice what went wrong and where improvement needed to be done. Development work and evaluation of experiments required a good deal of computing. I had access to our in-house IBM-360 system using FORTRAN-IV language programming, doing debugging by dissecting memory dumps if necessary. Over time, I got ample hands-on experience to fulfill my computing tasks efficiently, thereby gaining competent programming skills and fairly good understanding of system use.

Anti Aircraft Tank Gepard with twin 35mm 600 rounds/minute guns each. Notice the two muzzle-velocity measuring bases integrated on the muzzle brakes at the ends of the gun barrels.

My most important and largest project was the development of the Muzzle-Velocity Measuring Equipment FMV312 designed for the Anti-Aircraft Tank 'Gepard' - a self-propelled anti-aircraft weapon based on the company's twin 35mm, 600 rounds per minute guns. Besides the actual magnetic stimulus/sensing circuitry including required power supplies, it contained a special-purpose processor with an embedded 15-stage high-speed counter/accumulator for clocking the temperature compensated fly-time of the projectiles through the measuring base. It also included the computational means to check/arbitrate plausibility of the measured velocity and finally average the results per round. The result was fed to a ratio-metric analog/digital converter, imposing the velocity deviation onto the 400Hz signal of the fire-control system network. This equipment was entirely built from discrete components. The simulation and verification equipment belonging to the system was built using the newly available 5400-series TTL components.

I still feel privileged, that I could start my developer's career at - in hindsight - one of the most advanced electronics applications laboratory in Switzerland at that time. A footnote: The still compulsory military service at the Swiss Army was of some importance for me during the years 1957 through 1967, since I had to squeeze in most of my service time during vacations while studying. The some 690 days I spent on service duty, most of it as an officer, were useful nevertheless. I was trained to prepare an action, set up the necessary commands and then direct/control their execution.

Travel to the New World

Immigration and Work in the US

On June 6th 1968, I stepped out of the air-conditioned airplane in New York and found myself stuck in a stove - such felt the searing heat I had never before experienced in my life. "And I have come here to work?" was the anxious question I asked myself. Nevertheless, I felt happy, knowing that I would get picked up by a friend at Logan Airport in Boston. Our wives had spent time together in the same hospital room after delivery of their babies. This led to a loose friendship between us. My friend was just ending his employment at Polaroid Corp. in Cambridge - his family had left Boston already - to go back to Switzerland to join his father's business. I took over their rental apartment and bought their modest household inventory. I was lucky, now I had my place to stay, even including my own phone number.

In January 1968 I had applied for immigration visas together with my wife, our son of two years and our daughter of nine months expecting to wait in the pipeline for about one-and-a-half years to get the visas granted. We really got caught off-guard when we received our visas already in April of the same year. We also had expected some difficulties, not being able to name any relative or sponsor in the US, and having at our disposal only a tiny budget, which would barely allow covering all my expenses living in the US for four weeks plus buying a ticket back home, just in case. (For one dollar you had to spend 4.30 Swiss francs in those days.) My wife, born and raised in the same town as myself, had always loyally supported me. She consented to take the opportunity and face the risks involved by starting already the next day to organize whatever had to get done in time. And there was simply no time left worrying that I had rendered signature at the US Consulate General in Zurich, acknowledging that I could get drafted to serve in the US Armed Forces. (American involvement in the war in Vietnam had peaked that year.) And, of course, we felt relieved when I was assigned a draft status beyond any liability after I had been summoned by the Selective Service in April 1969.

After being settled - so to speak - I immediately began looking for a suitable employment, partially with the help of a placement agency. During the job search I got a pretty good overview of all sorts of electronics companies being located in the greater Boston area at that time. Although still alien to my new environment, I was really confident concerning my professional abilities. People appreciated that I took the risk of immigrating with my family and treated me favorably with openness, respect and trust. I was never ever subjected to any kind of harrowing tests or whatsoever. To give the interviewers some insight of my earlier work, I had the full set of schematic drawings and the detailed technical descriptions (authored by myself) of my FMV312 design at my disposal. I am still grateful about this most generous attitude by my former employer, granting me permission. After a three weeks run, I could choose among five offers. On June 27th I got formally employed (badge 5609) by DEC as design engineer reporting to Roger Cady of the PDP-8 engineering department. I had taken the first hurdle, and was relieved being able to inform my family to finally join me in our new life and place.

As a starting project, I had to design a PDP-8 interface to a commercial incremental tape (½") transport system. This gave me the opportunity to get to know all I/O-bus-related issues and the handling of PDP-8s. I also got familiar with all sorts of redundancy checks and error correction schemes. Following was a cocktail of smaller circuit-design tasks such as the development of a set of bus conversion modules, designing a very low-cost auxiliary power supply, hardening the design of disk read/write circuitry for production release, doing special debugging tasks on disk systems. Doing all this work I could expand my circuit design arsenal by progressively collecting know-how of the entire assortment of DEC modules. Meanwhile, I got quite familiar with the DEC organization in terms of knowing how to get things done efficiently. ^mill Before I got involved with the PDP-8/E project, I was assigned the challenging design work of the read/write electronics and control unit for the TU10 Tape Transport (2'400 feet, ½", industry standard, 45"/s, 7 or 9 channel). I applied an advanced scheme of quasi-logarithmic sensing, thereby alleviating the effects of the dynamic vacillation of read signals, and also reducing data skew. The control unit, a master-slave concept, was built using a production- and maintenance-friendly packaging scheme.

The PDP-8/E Design Story

Development of the Basic Machine:   The roads were smooth, the days were bright, the spirits high !

The front of a PDP-8/E (PDP stands for Programmed Data Processor) is actually a programmer's console consisting of a switch register for input, an indicator bank to show the register contents selected by the rotary-switch, and a few switches like 'clear', 'deposit', 'examine', 'halt', 'continue' for control: A very simple man-machine interface, indispensable for initial hardware/software testing.

"Like many successful industrial designs, the PDP-8 was actually a redesign." This quote is from the well-balanced, surprisingly informative, fun to read, testimony "The PDP-8" by John Voelker, published in IEEE Spectrum's 25th anniversary issue. (An article, enriched with the protagonist's quotes, still deserving top rank recognition.) Voelker's account gets to the point of our engineering task regarding this project. It praises the achievements of the people who had created, developed and launched the PDP-8 in the past. ^pdp8 We were entrusted to refine and enhance it for the benefit of the present and near future. I felt honored to be part of such a team. The PDP-8 history released us from arbitrating architectural system varieties. Instead, we had the obligation to preserve and guard compatibility for previous users and to breed substantial progress in order to generate new sales. Interestingly, the public perceived it as a totally new machine.

A key factor for a rapid realization was the OMNIBUS concept, setting a base for truly "concurrent engineering", a buzzword of the 1980s. (Which could only draw a weary smile from someone who was witness to this PDP-8/E adventure.) Marketing was involved from the start, soon followed by production engineering, software diagnostics and finally maintenance regarding functionality, producibility, assembly, testability, and maintenance issues. And only by doing procurement chores first by engineering, before extending to manufacturing, was it possible to ship 900 machines after just one year from the start.

Starting with initial sales of 100 (PDP-5s) for 27'000 $ each in 1963, by the end of 1967 sales of the PDP-8 and predecessors summed up to about 7'500 (at a final price tag of 12'800 $). The rate of 900 PDP-8/E sales for the first three production months (price <5'000 $) was a promising start for the contribution to the final sum of some 190'000 PDP-8s sold.

Following is an overview to help classify the various types of this unique 12-bit word machines developed and built from 1963 till the end of the 1980s. (With the emergence of the 16-bit word machines the word-format of the PDP-8 - not conforming to the established 8-bit byte mainframe standard [1964] - was considered outmoded for tangible reasons.)

• The original type PDP-8 was the first successful commercial minicomputer, and it was built using discrete components. The PDP-5 was its predecessor. The PDP-8/S was built as a compact tabletop unit with serially (vastly slower) working CPU.
• The advent of Transistor Transistor Logic (TTL) allowed to implement the PDP-8/I with medium-scale integrated (MSI) circuits, featuring better performance than its predecessors at lower cost. But its design, still using small Flip Chip modules and a wire-wrapped back panel instead of a more adequate packaging scheme, did not fully exploit the new technology. Burdened with this handicap, it could only serve as an intermediate solution. The PDP-8/L was the compact tabletop version with similar performance but limited capacity.
• Still using the same MSI circuits, a fundamental change was the introduction of a new I/O bus, the OMNIBUS, together with the striking modularity of the PDP-8/E packaging scheme. It allowed customers enormous flexibility in expanding their systems' peripherals as well as reducing cabling and packaging requirements. The PDP-8/M and the PDP-8/F OEM versions could be best described as a half-size PDP-8/E (one OMNIBUS backplane only) with identical performance. The later PDP-8/A model was equipped with semiconductor memory chips and its circuitry was condensed on larger boards.
• With the CMOS-8 series, very-large-scale integrated (VLSI) single chips, the 6100 and 6120, were used to implement the PDP-8 architecture into hundreds of thousands of VT/78 and DECmate video data processors and workstations.

For general information about the PDP-8 family of computers and for detailed technical documentation of the PDP8/E design refer to:

The Project     The Project started in February 1970 with a bang. Everybody was caught by surprise when Don White came up with a fully manufactured OMNIBUS assembly and a PDP-8/E specification. This 25-page document was written in a hands-on style for insiders, but was extensive enough that work could get started immediately. This boosted morale of the group tremendously - and this was good. Since our engineering manager Roger Cady had left to direct the development of the first PDP-11, our group lingered in some sort of an interregnum, and was gradually losing orientation.

The OMNIBUS was capable of accommodating up to 20, 38 ,56, or 72 modules depending on the number of the 20-slots assemblies used (an Expander Box was necessary if more than two were required)

In almost no time a mock-up of the new machine was posted. This quickly became sort of a forum for technical discussions among members of engineering and marketing, which was located on the same floor right next to us. The self-evident, self-explaining PDP-8/E concept, paired with its unique industrial design solution was an instant hit. Marketing people and their long-lasting customers were very much relieved at first; soon they got outright enthusiastic about their newly won potential to fulfill their needs. Only a short time before, they were stuck in a strategic deadlock. Attractive alternatives, from external competition as well as from the newly launched PDP-11s had begun to show up. But unattractive prospects of software porting for any of these alternatives clouded their future. With the then existing PDP-8/I models - although equipped with the up-to-date MSI circuits, but penalized by its poor packaging scheme in terms of size, cost and expandability - DEC was not in a position to counter some of the very efficiently built equipment from competitors. In other words, a large, loyal customer base felt abandoned. Most likely, many of them could have got lost as DEC customers for good. For them the sky cleared up; for us it rendered a foretaste of things to come in terms of mounting deadline pressure.

Development began with only Don White together with Lou Klotz working on the CPU and myself on the memory. It was a reflective phase with little distraction, rendering rich results. Just in time we got our new manager Dave Chertkow, hired from outside the company. Together with his assistant Ken Pierce and our indispensable, caring secretary Penny Smith, our group's top was complete again. Dave took the helm in no time. Soon he assigned fitting tasks to PDP-8 technicians and brought new people on board as required. He did a great job keeping our engineering potential at its best, by alleviating us from any chores which could get done by somebody else. He acted as a gifted promoter of the PDP-8/E OMNIBUS concept by actively supporting marketing to woo new customers. He then launched numerous OMNIBUS options, allocating whatever resources seemed fitting to him.

For us developers the overhead was kept absolutely minimal, there were no schedules, only deadlines ! Although we did not feel any budget pains, we sure had to pinch out any possible penny from our designs. Communication was simple and direct. I cannot recall a single design meeting during this period except the official Design Review.

Design Reviews were held by the design team under the auspices of the chief engineer. One had to win the attendance of persons from marketing, production, quality control, software diagnostic, and maintenance. The individual from production was to take minutes (for good reasons). Our Design Review was convincing and ended as a success. However, a cost reduction was requested, and we were given ten days to realize it. Not everybody was happy about that. Regarding the CPU it meant that they had to take out a few of the goodies they had proudly presented. I considered it a gift to have a few extra days available in order to get rid of e few irritating inconsistencies in my design and to have the legitimacy to further search for some better and cheaper components.

PDP-8 engineering was special: Practical expertise, team spirit, willingness to put in extra efforts, mutual recognition, maintaining fresh humor and be good sports were the name of the game.

CPU and Basic Peripherals     The design of the Central Processor Unit (CPU) consisting of Major Registers M8300, Register Controls M8310, Timing Generator M8330 was done by Don White in collaboration with Louis Klotz, a production veteran. The two perfectly complemented each others PDP-8 CPU know-how, warranting compatibility and still providing maximum possible functional extension of the basic machine. Certainly no easy walk - but Louis the "living simulation robot", playing-off his debugging virtuosity, made life a lot easier. Don also took care of the Bus Loads M8320 and Programmers Console with assistance by Greg Esser. The Teletype Control M8350, functionally a UART device built of MSI components, designed by newly hired John McNamara, completed the basic machine's board set (memory excluded).

Also under supervision of Don and Louis with the assistance of Larry Narhi, the high priority External Bus Interface Control Options KE8-E/KD8-E for Programmed Input/Output and for Direct Memory Access (Data Break) as interface to PDP/8I and PDP-8/L type peripherals (legacy type hardware) were realized. Besides - after he had already completed the schematic of a Switching Power Supply - Don prepared the technical part for the outsourcing of a Linear Power Supply and supervised the mechanical issues of the equipment box with the support of Paul Gardner.

PDP-8/E Timing Generator for processor and memory signals.

Timing     Working on the memory design I was compelled to define the machine timing in full detail. In his specification Don White had defined some very useful timing details, such as changing time state in the center of a 100ns pulse. He had suggested using delay lines for implementation as it was common practice. Rather than start a question/answer ping pong, I decided to communicate by sketching a possible circuit, reflecting the exact timing scheme I considered adequate. On this occasion I also designed the circuits I felt apt for properly driving the OMNIBUS signal lines including the appropriate termination. The kernel of the gear was a serial shift-register driven by a 20MHz crystal oscillator. Don White's response was simple. He pasted my timing proposal, unmodified, right onto his Timing Generator M8330 schematic and transferred the termination details onto his Bus Loads M8320 board.

Memory Expansion     When Dave Chertkow asked me to design the KM8-E Memory Extension and Time Share Control module I felt relieved. Development time was running out for this important option, which provides the CPU with necessary means to control memory access beyond its intrinsic 4k memory space, up to the maximum of 32k. Moreover, some minor logic for time-share systems had to be included. While designing memory and timing, I was forced to very carefully take all circuit delays into account which possibly could affect address and data signals. I had no choice but to mentally evaluate the appropriate signal paths required by this option, to make sure things would match. In other words, I preferred doing the design of something I knew already how it was to be implemented, rather than taking any chances. This piece of hardware is not too complex. The contents of two three-bit registers (for insiders: Data Field, Instruction Field), preloaded under program control, are to get directed through a machine-state controlled multiplexing scheme to the drivers of the three address lines required for the eight-fold extension of the address space. Transforming this logic into a schematic was business as usual for me at that time. Then, together with Dick Madden, we verified this partial design with that of the existing predecessor, the PDP-8/I, by marking up all the functionally matching circuitry on the relevant schematics. The remaining loose ends led to the modest arbitrating logic for directing address information in function of relevant machine states. We ported the identified arbitrating circuitry into our design without even bothering to check its functionality, completing our design in less than a week's time. Now Dick took over to have this option prototyped. Debugging it, he had to correct two mismatched connections of the arbitrating logic.

Memories

On the historical finish-line of a 20 years old technology or Core Memory's last battle, pushing its success to a veritable sales surge before surrendering to the semiconductor newcomer

The standard PDP-8/E memory is a non-volatile random access, coincident-current magnetic read/write core memory. Its cycle times are 1.2 µs for read-only access (fetch and defer cycles without autoindex) and 1.4 µs for read/modify/write access (all other cycles). Its storage capacity is 4096 (4k) 12-bit words per unit. The memory is expandable in 4k increments up to 32k words. The small .020" toroidal (ring-shaped) magnetic core storage elements are mounted in a 3-wire planar configuration.

Shown here is a dismantled 4k x 12-bit word MM8-E Memory consisting of the Sense Inhibit G104, Memory Stack G619 and XY Driver G227 boards. This souvenir set served as the author's personal production release reference system. Through all the years the author has proudly put up this set for display in his office.

Unlike the price/size/speed/capacity race for non-volatile bulk or mass storage which later took place between magnetic (disk) and semiconductor (flash) technologies, the race for work memory between magnetic (core) and semiconductor (DRAM) devices ended before it even had started. But due to the special circumstances, DEC enjoyed a last surge of a very profitable magnetic core memory production, which lasted for about four years. Reliability and outstanding low cost-to-sales ratio - one of the best guarded secrets at DEC which very few people knew about - enabled postponing the surrender to the semiconductor newcomer for the benefit of the company (not just in terms of profit). The first feasible semiconductor bulk memory chips, the 1103 1k-bit PMOS dynamic RAM IC was first available for prototyping in 1971. Reliability under required operating conditions got not reached until about 1972, and attractive pricing for DEC was not achieved until 1973.

State of the Art     At the time there was no feasible alternative to magnetic core memories for non-volatile, fast, random read/write access. With regards to packaging and testing - important aspects for efficient, reliable production - convincing implementations were still lacking. I was not enthusiastic about what I saw, including the new designs. Apprehensive about crosstalk, the common belief, that low-signal sense circuitry should better not be placed on the same board with 400mA current-drivers, led to unwieldy packaging schemes, including twisted-pair wiring. Testing and tuning had to be done by well-trained technicians in time-consuming procedures. Core memories appeared to be too costly, indispensable analog/digital devices, at odds with the digital world.

Theory and Research     Without any particular intention, since fall 1968 until the end of 1969, I had collected and partially studied every technical article about core and semiconductor memories which I ran across in magazines. I just wanted to be informed in a field, which seemed very important to me while working for DEC. When I was asked to design the new memory system, I immediately started to expand my research by ordering copies of all relevant literature I could identify (50 publications ! ^cores) in the excellently researched and informative book 'Digitale Rechenanlagen' by Ambros P. Speiser. I began with the systematic combing of these papers in search for fitting know-how to allow for simplifications on the design and also to enhance reliability. Accompanying the actual design work, I focused my studies on related topics available in the papers. And, of course, I did carefully study the just completed PDP-11 memory design. Combined with my knowledge acquired in my pre-DEC work, I indeed felt well prepared to reach the goals I had set myself.

Design     While doing design work, I made crucial decisions, and I also set up and refined my own planning:

• Stay with the core size .020" for a 4k stack. Put aside the idea to go to the reduced .016" size for a possible 8k memory. Keep this tempting possibility for yourself in order to avoid stirring appetite in marketing.
• Use as many parts from the PDP-11 memory fitting my design, notably the same core type. Using a proven core technology for operating a 4k by16-bit word memory (PDP-11) but applying it for 4k by 12-bit words (PDP-8) only, rendered extra solid margins (+25%), making the 'no-tuning' goal achievable.
• Devise a scheme avoiding individual interdependence among the three memory boards. Interchangeability must be kept intact under all circumstances.
• Devise a connection layout such that boards of a dismantled system open up connection loops, allowing a memory tester to interfere inside some specific circuitry. Enabling for instance varying xy-currents, sense thresholds and so on.
• Do not tolerate the use of any potentiometers. None of that tweaking and tuning anymore ! (Some four to five trim elements were commonplace on core memories.) Tuning-potentiometers facilitated a hasty designer to hide incompetence, inexactitude and incompleteness behind it, shifting undue burdens to production and maintenance. (Also a manager's nightmare: 'Always almost finished' !)
• Make provisions that initial CPU and memory testing could be done independently. Therefore, build two PDP-11-based memory units, one with an OMNIBUS-compatible interface reserved for CPU testing, and one with an interface, matching requirements of off-the-shelf memory exercisers.
• Include as a design feature a concept of an automatic memory testing.

The author (left) in a memory test session assisted by Dick Madden. (Extracted from DEC Public Relations Department: "on line" monthly publication August 1970, p. 2)

This elaborate planning was a result of my permanent concern of how this piece of equipment would get produced, tested and how it would succeed in the field. Now I was ready for the actual design. The only design blip requiring academic level skills was the computation of the optimal read-wire termination using the Laplace transform method. The rest was doing puzzle work, minimizing parts count, slashing costs wherever possible, standardizing, harmonizing, figuring out testability, forming layout details, making it look good. A sort of 'form follows function' process, I loved to do.

What might appear a straightforward three-board memory set is by no means self-evident. The then common practice initiating layout work by 'Give them the schematic, they will do the rest for you.' would have been unrewarding in this case. Considering locations of signal lines on the bus, there existed one and only one solution for the proper placements of the components on the three boards. It boiled down to a three-dimensional puzzle only the design engineer himself could reasonably put together. Having done that, it was essential to prepare for a smooth course of the layout work required. I informed the supervisor of the model shop in advance, winning him over to schedule one of his top layout technicians to do the whole three-board memory set. The ability to place components in a layout advantageously - also an aesthetic matter - distinguished a top man from others. It was vital to instruct this man very carefully, making him forget that his expertise, which made him top, was not sought in this case, making him accept a set of rules for dealing properly with low-signal sense circuitry mixed with high-current drivers - and still arouse the necessary enthusiasm for achieving an impeccable result. All had to fit in a first pass. Underestimating these aspects - as it happened with the CPU set - could lead to disappointment, seriously endangering deadlines.

Prototyping and Test     My assistant, Dick Madden, had designed, built and checked the two temporary memory units, one with an OMNIBUS-compatible interface reserved for CPU testing, and one with an interface, matching requirements of the off-the-shelf memory exercisers in time. Besides, he helped me perform pretesting of some components and circuit parts. Once we had got the first prototype memory boards from the module shop, we could immediately start testing. Making steady progress, asserting expectations, was gratifying. For the sake of additional cost reduction we also tried an alternative scheme which would have substantially cut xy-driving circuitry. It essentially worked, but marginal recovery of the driver transformers, or alternatively requiring longer cycle time, urged us to abandon the alluring bonus.

This fully automated memory test station performs dynamic testing of the Sense Inhibit G104 / Memory Stack G619 / XY Driver G227 board kit as well as the assembled MM8-E memory system unit. Tests such as 'address', 'data' and 'worst case delta noise patterns' are run as well as typical operating characteristics under control of a PDP-8/I computer. On certain tests, xy-currents, read detection level and sampling time are varied within and beyond the defined operating field limits. The corresponding results are then churned out on Shmoo Plot charts as vivid certificates of the attained operating margins. This five minute per unit testing technique allowed no variation in quality; no marginal units survived these tests.

Later, one incident almost wrecked this success by forcing delays, setting unrest, anxiety and endangering our reputation. Our preproduction batch of memory stacks, some 25 pieces, were supplied by our preferred stack vendor, with whom I had successfully completed the stack design in collaboration. To maximize profits by enhancing yield at lower cost for prospective volume sales, they could not resist the temptation to recklessly change the production process without properly informing us. The result was a disaster. These stacks were tainted by magnetostriction, thereby generating not easily identifiable disturbances. Fortunately, we were already in the process of gearing up three additional sources, which allowed us to readily reduce the supply gap.

Parity Option     I did not mind when the politely formulated assignment to design this option fell into my lap. I knew I had to squeeze in this unplanned job somehow, but I also knew it was rewarding work I had superficially envisioned before. This three-board set would contain a regular stack board of which only eight of the twelve bit-planes would get used. Each of the bit-plane used would provide the necessary 4k of a 13th bit per 4k memory field. One MP8-E Memory Parity option would therefore serve the whole address range of 32k words. Since the field-select circuitry was located on the Sense Inhibit board, providing the resulting select signal to the xy-Drive via the top connectors, the xy-Drive board could also remain standard. Therefore, only the Sense Inhibit board needed modifications. Sense Inhibit drive circuits had to get curtailed from twelve to eight, providing ample space for parity and input-output logic. Proficient in drawing I rapidly set up a detailed schematic. Again, Dick Madden took over to have this option prototyped and tested.

Memory Tester     Bob Regan became responsible for the whole MM8-E Memory tester from design through build and test, as well as for introduction/training of production people. Concept and specification were defined in a few informal meetings with me. He was also encouraged to tap know-how from anybody he felt fit to help him get the work done. He sure delivered a fine result.

The tester had four distinct ports, three for each of the single boards of the kit and one for the whole system unit. Including the respective 'device under test', each of the three board-ports consisted of a full memory unit. In each case two of the boards were part of the tester. With a clever wiring/connection scheme these ports had simultaneous connections to the regular, tester-manipulated OMNIBUS, as well as to some distinct circuitry to control xy-currents, read detection level, sampling time and operating voltages. For the system-unit-port a regular OMNIBUS access was sufficient, since the complete unit was run under normal operating conditions but with all relevant diagnostic software. The tester-specific kernel actually consisted of slightly modified PDP-8/E memory components. The rest was a standard PDP-8/I equipped with some special interface hardware to operate the OMNIBUS plus some auxiliary off-the-shelf equipment.

This integrated test concept, combined with a restrained performance/capacity design policy, was a key factor for the outstanding reliability and the extraordinary low cost-to-sales ratio of this core memory.

The OMNIBUS Vehicle

What it's all about

The OMNIBUS - conceived in engineering team collaboration - consists of a number of connectors mounted on a printed circuit board (PCB), replacing the then commonly used wire-wrapped back panel with its thousands of wires. Each pin-number on any connector is associated with the same specific signal line. Thus, any module may get plugged into any of the connector-slots. If a functional unit requires more than one module (such as the memory), connectors on the top of the boards serve as internal links. Where required, connectors on the side of a module allow inserting cables to the "outside world". This scheme - adapted in countless equipment over the years - eliminated once and for all the thousands of wires previously required on back panels of preceding models. During implementation of this bus, there was plenty of headwind to be endured, coming from many directions, ranging from skepticism to outright disbelief, until hundreds of machines got out the doors. Don White knew I was his dauntless ally. He had been quite impressed at my job interview when showing him my own reference design, where I had already applied a partial bus system, substantially reducing wiring and enhancing functional modularity.

The 5'000 wires required in a PDP-8/I back panel (right) are eliminated in a PDP-8/E OMNIBUS^TM back panel.

Already at the start of the project, Don had laid down the full definition of the OMNIBUS. Alterations were never required. And most important for a smooth project start, he had already prudently assigned the physical location as well as the logical functions of all bus lines. After I had taken care of the timing generation with the further electrical bus details, I felt being in charge of fostering any electrical issues regarding the OMNIBUS concept.

Its uncompromising concept of unrestricted free handling was of pioneering quality. It was also a proof that it worked with straight back-plane bus connections only. Moreover, because of the foreseeable progress in integrated circuits any future design could be regarded a subset of the OMNIBUS, in terms of the number of signal lines as well as its expanded length. The functional and logical organization was pragmatic, parts-saving, performance-squeezing and unabashedly application-friendly for programmed I/O applications. The set of the signal definitions used was not at all suitable for future standardization. It could only serve the then prevailing technology applied in a synchronous PDP-8 structure. Once medium-scale integration would get replaced by denser circuits, this approach would only survive during a transitory phase.

Electrical Characteristics     Against all skepticism due to the staggering number of signal lines (96), the OMNIBUS scheme was hard as a rock in electrical terms.

• The OMNIBUS assembly as such, is of an electrically homogeneous, low-impedance design.
• The interconnections of all ground pins (31) on a board complement longitudinal wiring with the appropriate cross-connections to form an almost ideal grid, growing in size simultaneously with a growing number of boards.
• Clustering of all register signals of one sort in one place was diligently avoided. As a worst case up to 15 high-to-ground signal transitions could take place within a few nanoseconds time, forcing tremendous displacement currents to be absorbed without generating too much noise.
• With the address-select scheme applied, signal switching would only take place on the selected module, the rest staying calm, therefore dramatically reducing switching noise. Example: A 32k memory size would occupy 24 slots, but on any access, possible switching activity would be curbed to only two slots (the stack board having no signal connection to the bus).
• The load-relief technique applied by the device-select scheme kept DC-loads low even with numerous options installed.
• The synchronous, determined timing scheme, providing well defined setup and clocking signal transitions, was averting any confusing or unpredictable signal patterns thereby banishing switching noise at incongruous times.

This comparison among the bloated OMNIBUS (96 signals) and a "global" type bus (some 36 signals) illustrates the effects of address/data multiplexing and the hiding of "internal" signals.

Diligence was required to maintain bus integrity. In case a designer used the interfacing circuits of one of our basic options as a template, most everything was ok. However, I felt obliged to observe designs in a watchdog-like manner in order to prevent compromising the OMNIBUS scheme in any way. Although I was keeping notes, it was not before the middle of 1971 that I finally got free time to write down the binding electrical OMNIBUS Specification. ^spec

Functional Perceptions     There is no such thing as an ultimate bus system. The OMNIBUS was just one large, versatile, externally accessible data multiplexer system with inherent synchronous timing features. Some special control signals allowed also asynchronous operation for peripheral options but not for the memory. Besides carrying "global" type bus functions like doing address and data transfers, it provided all sorts of normally "internal" control signals for accessing CPU resources. Ultimately this assured warranty for full compatibility to any earlier internal application. In fact a bus participant was able to run the machine in "phantom" mode, autonomously forcing instructions. For normal applications, a designer needed not to understand those "internal" signals. In fact, he better disregarded them, so as not to get unnecessarily confused. The separate memory data signals MDnn, somehow redundant to the data line signals DATAnn, give rise for further explanation even in retrospect. Considering earlier PDP-8s (even PDP-5) - still built with discrete components - this scheme allowed to save expensive register-banks (flip-flops). It also rendered the benefit that the memory data MDnn - in metamorphosis - served as addresses for I/O instructions. At that time, a harmonized structure using memory-mapped I/O would have led to excessive costs.

With large-scale integration (LSI) being in sight, we put in efforts to be prepared regarding an adequate bus system detached from any PDP-8 structural handicaps. The preliminary bus system proposal ^x-bus, employing address and data multiplexing as well as matching integrated circuit packaging requirements, offered a feasible scheme for implementing a CPU using large-scale integration (LSI). It pioneered the popular Q-Bus (also known as the LSI-11 Bus) first used on the LSI-11, then also on VAX systems.

The PDP-8/E Arena

About struggling to success:   Bumpy roads, heavy traffic, stormy weather, nothing would stop the trek to go on and on !

The days of more contemplative design phases were over for good. More and more time was spent in the lab in a busier, more heated (i.e. not air-conditioned) atmosphere. Gradually, the entire PDP-8 engineering crew got also involved: Al Czajkowski, Al Deluca, Ashwani Chadda, Remi Lisee, Owen Fisk, and Bill Hodgdon doing development of major peripheral controls. Then, versatile technicians like Mel Arsenault, Rod Sutherland, Bruce Hanson, Paul Kotschenreuter, Dave Adams, Mike Kozak were doing prototype checking, building and checking the seventeen preproduction machines scheduled for delivery during September 1970 to prime customers, and, if required, would take care of environmental testing and quality control. Finally, there were frequent guests like diagnostic programmer Ed Steinberger and system programmers Chuck Conley and George Berry or Stephen Kallis Jr. writing on one of his timeless, vivid technical booklets. Necessary and increasing interaction among all these people became sometimes challenging. Uneasiness prevailed, that management had perhaps not fully anticipated this unavoidable change of the work pattern and style, and that appropriate provisions seemed to be lacking.

Test of the Basic Machine    The actual tests of the basic machine went according to plan. By the end of June, the bench prototype (using PDP-11 memory) was performing as expected and could soon be presented running its own memory. Next, those high-priority External Bus Interface Control Options, such as the interface to PDP/8I and PDP-8/L type peripherals were mastered. It was absolutely indispensable to perform diligent and comprehensive checks on all related peripherals still for sale in this new constellation. Things worked out to our satisfaction except for one peripheral device, which was using direct memory access in a most stochastic fashion. Every once in a while - hours, days - an error would show up on a fully loaded disk drive not directly related to the dubious equipment. What a nightmare ! It appeared as a "random" error, but nothing is random in computers. Any malfunctioning is due to flawed designs or marginal components. Catching this bug devoured most of our capacity for a long time, a too long time under the circumstances. While I was plotting trap programs, Louis was virtuously playing the programmers-console keyboard implementing and setting them up. Then, we were compelled waiting for a next error event. Working step-by-step, again and again, like hunters, until we caught the culprit. The designer of the faulty equipment had allowed himself to spare full decoding of memory addresses, inexcusably compromising common ground.

In Charge     Returning from the 1970-WESCON exhibition after a two weeks absence from the Maynard plant, I noticed a team with spirits as low as never before - the contrary what I had expected after this successful launch of the new machine. Of course, meanwhile the deadline pressure had built up. But the real cause for the black mood was that adequate supervising of the group by engineering management had ceased dramatically. Furthermore, due to some medical problem, Don White had to retreat from everyday business. In other words, the group was essentially missing their two leading individuals. Now, the alarm bells started to ring ! Alone the thought that all this great work could end up being compromised, and that instead of a humming production floor there would be doldrums, made me feel absolutely sick. Lamenting was not my thing. Avoiding any bad talk, I got to work even more focused than before. I actively began to support my fellow workers solving technical hitches thereby prodding them for crisp, system-consistent solutions. Gradually they cheered up.

Shortly, one day during September 1970, Dave Chertkow came to see me while I was working in the lab. He asked me directly, if I would be willing to take over as Project Engineer and serve as interim PDP-8 group leader, replacing him in his role. He himself would switch to PDP-8 marketing, a position - I knew - he was destined for. I gave him my immediate 'Yes'. I did not even ask on what terms my new position was to be compensated. As it was to be expected, DEC treated me very fairly. After this five-minute conversation, I was the appointed Project Engineer for the entire PDP-8/E development. In this position, I was responsible for getting the PDP-8/E into mass production. This included directing the development of internal options and peripheral controls from design through production release. That was a pretty hefty responsibility. In carrying out the above assignment, I had to directly supervise some 10 engineers and technicians. Then, I had to be accessible to the many persons of all disciplines which expected professional support when addressing their mostly technical issues. I did not feel this to be a burden. Having unrestricted control over a project you are one hundred percent convinced of, can be gratifying. Also, my professional and military background in dealing with all kinds of people, proved helpful. First, I had to straighten out a few personnel issues. Some members of our crew came under fire for justifiable reasons concerning results they delivered. However, it would have been unfair curtailing their professional careers, considering the apparent supervisory deficits reigning during that time.

During the fall I could attend a Supervisor Training Course given by Harvard's Larry Bennigson. In small, team-oriented case studies I could acquire some useful managerial skills. Also, I was introduced into the company organization by DEC management. To my surprise - against daily experience with rather chaotic organizational patterns - important rules and demanding processes existed as guidelines in a most detailed fashion. One was urged not to let subordinates know about these written rules. Nobody's individual initiative should get strangled; nobody should feel entitled insisting on rules rather than do what had to be done.

Getting it into Production     A few days after my designation I found myself, alone, answering questions to some 20 people in a production meeting. It sure was legitimate to exhaustively ask for first-hand information about the project at this point. Nevertheless it was a tough piece of work that morning. But I never blinked. I already had had the chance to build trust with some of the individuals present at that meeting. They knew me being always supportive, not letting them down. They knew I was sincerely proud of their PDP-8/E assembly line, anticipating lots of machines going out their door. The meeting got closed with a sense of mutual understanding, respect and helpfulness.

When building and checking the seventeen preproduction machines by engineering, we let Bill Miller and his people from production engineering participate in the process for early familiarization. Then, production began manufacturing boards before engineering had granted production release, thereby shouldering the burden of having to supplement some of the boards with wired fixes. They had no other choice. They needed production parts early enough to build up some inventory, check out production testing facilities and train their personnel in time to keep the monthly shipping deadlines from December 1970 through February 1971 with 200, 300 and 400 machines.

I was anxious to provide production with our fullest support possible. During the whole introductory phase of several months, I had situated my guys in fitting spots on the production floor. In a mix of training production personnel, helping them test first batches, upgrading test equipment and trimming procedures, they could ensure that learning was efficient and that communication with engineering was always possible. Dick Madden and Bob Regan were assigned to memory testing, Dave Sari for processor testing, Jack Grieve for automated product testing, and Tom Pittman for the acceptance line. During all these hectic months, a smooth, fruitful collaboration under a most trusted spirit took place between production and engineering.

Options, Options, Options     Options mushroomed, initiated not only by engineering but also by marketing to cover their customers' needs. The self-explaining PDP-8/E concept and its clever industrial design, offering common infrastructure as well, had reduced overhead and enormously enhanced capabilities for applications. Apparently, the developers' inventiveness and creativity got stimulated so intensely, that the total of standard peripherals culminated finally at over 70 items. Although some of them got rapidly obsolete due to accelerated progress in semiconductors.

At the beginning of December - the month during which the first 200 machines got shipped - the prospects for timely delivery of options were mixed. The four basic options, designed by the kernel team, had either been already released for production, or they were under final rework. Regarding the sixteen major peripheral controls, done by our crew, the delivery forecast varied between ready, timely, and two months.

A then unknown number of options were in the pipelines beyond the sphere of the PDP-8 product line. I was determined to funnel all of them through a technical release procedure controlled by PDP-8 engineering; nothing would escape the alert eyes of Louis Klotz. I let him build a lockable cage (one of the very few locks in the whole plant) with a complete PDP-8/E system inside it, and he possessed the key. Direct access to the cage was granted only to very few trusted individuals, among them Chuck Conley for testing of his OS/8 operating system. To grant production release I needed a positive oral report by Louis of his hardware compatibility tests, assurance by Chuck that OS/8 system tests still ran uncompromised and the certainty of a permanent installation of this new option in the "super system". Beforehand, the actual designs got approved by me informally. I usually went to see the developer at his place, letting him explain his design to me. I was fast in spotting any interface inconsistencies and demanded according changes if necessary. Concerning the design part representing the inherent functions of his device, I would nudge him to get rid of patterns and details I considered insufficient in terms of design, producibility or testability. Most often a module ended with fewer parts after my short visit. Generally, my interventions were welcomed, some even appreciated it. Like John McNamara who highlights in his communications book a Transition Detector, an outcome of one of my purging actions. Although being defiant at times, I always was anxious having won a friend and not bred a foe.

Cost Reduction and further Development    In 1971 John Clarke, a likable personality with grips and experience, became engineering manager of our group. John would serve this engineering group, which later designed the various workstations, for many, many years to come. Complementing engineering capacity was John Kirk, who later designed the PDP-8/A. He joined us after having worked for DEC in England during several years.

There was plenty of 'meat on the bones' on a PDP-8/E with its large, expandable box for customers not needing full capacity. Therefore, the PDP-8/M as an OEM version was launched, which contained one single OMNIBUS backplane only. The design boiled down to a mechanical restructuring, therefore Paul Gardner, our mechanical designer, was assigned project engineer. We applied an adequately scaled-down, switching-mode power supply. A new supply-design group had been initiated, and they were eager to provide us with a fitting module according to our specifications. Novices in terms of predictable power-up/down behavior for uncompromising data retention under all circumstances, they needed my personal monitoring of their design. The machine was equipped with a one-switch one-light panel for starting its integrated Bootstrap Loader - a tiny program for loading paper tape software - implemented as a read-only memory consisting of a discrete diode array. This enabled an OEM customer to load his fully tested program without the need to buy the costly Programmers Panel and to even protect his equipment from undue manipulations by his end user. For test and maintenance purpose, the use of the common Programmers Panel was still possible. The PDP-8/F - actually a marketing distinction - was essentially of identical design.

During 1971, in a rather casually operating ad-hoc team, various feasible new architectures for a new machine were outlined. It was all brainstorming, very interesting, even though producing no tangible results. But it offered unbiased opportunities to peek into new technologies, detached from routine business. On several visits at the Los Angeles based North American Rockwell (now Rockwell International) Semiconductor Division, Louis Klotz and I got a first-hand introduction into microprocessor production. Not widely known in the scene, they were producing integrated microcontrollers for military applications, before similar commercial parts got even publicly announced. These insights provided the essentials for a bus system proposal employing address and data multiplexing, compatible with integrated circuit packaging. In a paper - still using the PDP-8 as a vehicle - I laid down a preliminary specification of such a bus system. ^x-bus

Epilogue

Life after DEC

In April 1972 I left DEC to work for Balzers AG (nowadays Oerlikon Balzers), a leading company in ultra-high vacuum and thin-film coating technology, located in the tiny Principality of Liechtenstein, neighboring Switzerland. I was in charge of development of a novel digitally-controlled, computer-compatible Quadrupole Mass Spectrometer. First introduced at the 1973-Achema Exhibition in Esslingen, BRD. Its concept of versatility and outstanding performance (of course equipped with its own special bus system) was well received, sales took off immediately, and its product life extended to well over a decade.

In 1974 I founded my own engineering company. Starting alone with a rather large real-time software design project, I soon could acquire customers for hardware too. The company grew rapidly to a well-balanced crew of about 10 people, a size I maintained over the years, a size allowing me to do some engineering work myself all of the time. My company became a DEC customer almost from its beginning. We used all sorts of LSI-11 and VAX hardware/software extensively in our special products and for in-house use as well. During the late 1970's and the 1980's, DEC regularly commissioned my company in helping to take care of numerous compliance issues with European Safety Standards for their power supplies regarding the PDP-8/A line and all sorts of DEC workstations. Over the years we had the pleasure to host several PDP-8 group members visiting our place, either for business reasons, privately, or both. Of course, during each one of my few US visits, I went to Maynard to see "how the guys were doing" over at DEC.

Special life-long friendship grew out of the numerous visits with John Kirk and, particularly, with John Clarke. Together with his wife Marcia, he visited the old continent many times over the years.

Afterword

On why I took up my pen

• A friend of mine - we studied together at the ETHZ - motivated me taking advantage of this very special IEEE Global History Network, First-Hand History forum to make a contribution of my own. This aroused my curiosity, and after he had given me a practical introduction of how to proceed on this generous platform, I was on-board.
• Then I have to admit, that I got to like the idea that someday, some of my eight still young grandchildren might pick up a copy and be surprised to find a professional horizon of their grandfather somehow broader than gardener with a knack for vintage motorbikes. And how impressed they would be, finding out what their admired grandmother - as a young woman with two babies to take care of - had accomplished, having supported her husband in every respect with grace, never ceasing optimism and an incredible energy.
• A history buff myself, I then began to perceive, that I may have some obligation to contribute to this very special slice of electronics history. Withholding my recollection, omitting publishing technical information not otherwise available, thereby undervaluing the efforts of all my colleagues and contributors in the struggle for success, would have to be most likely graded as neglect.
• Evidently this story testifies the coincidence of several seasoned electronic technologies culminating in a single piece of an iconic industrial design which deserves status by its own merits. TTL technology applied in small-scale (SSI) and medium-scale (MSI) integration together with core memory technology rendering prospering life for an already seasoned, perhaps most elegant ever invented, minimalist work of logic in the new form of the PDP-8/E with its OMNIBUS-based versatility and simplicity.
• Then, there are all these enthusiastic collectors of PDP-8 machines with related equipment, software and documents, contributing their means and time for the preservation of most precious historic material. If this story could bring them any insight they deserve or even be of some help on their undertaking, it would be of greatest satisfaction to me.
• After all this is a tale and an appreciation for a bunch of wonderful, proud, focused people, serving in a remarkable company environment with hot marketers, clever engineers, motivated sales people, hardworking production and helpful service personnel, struggling and giving their best for their common goal of rapidly getting loads of new machines out of the door.
• Finally I hope readers will have fun while riding this OMNIBUS. For me it was a call for an encore after an exciting play.

References

Big help from people who did not know they did help ….

Salt and Pepper

Tales, some serious some funny !

Copyright © 2013 by Remo Vogelsang