The work that led to development of the first practical videotape recorder did not flow from a divine inspiration or a miraculous breakthrough onto the road to success.

That first videotape recorder was the product of over four years of hard - and at times, inspired - work by a team of individuals who brought their own unique skills to bear on the endless problems that confronted the development team. At times, progress was slow - and twice the project was put on the shelf.

And, as it turned out, much of the real work began after we made our first successful demonstration. But that was all in the dim future back in 1951.

In October of that year 1951, after several disputes on the question of how television recording might be accomplished on magnetic tape, Alexander M. Poniatoff, founder and at that time president of Ampex Corporation, and Myron Stolaroff and Walter Selsted, his two top technical aides, agreed that a relatively small sum of money should be appropriated for the purpose of investigating a rotating head approach.The rotating head method was one which had been discussed by Stolaroff with Marvin Camras of Armour Research Foundation, of which Ampex was a licensee. The discussions engaged in by Poniatoff, Stolaroff and Selsted were concerned with the feasibility of such a system as opposed to other approaches, notably high speed techniques and time division multiplexing schemes. Accordingly, a project was authorized in December of 1951.

The opportunity to join Ampex to work on the project was one that I jumped to accept. Prior to the actual start of the project, the conception of the system was merely this ... three heads were to be mounted on the flat surface of a drum, scanning in arcuate fashion the surface of a 2-inch wide tape. The head-to-tape speed was to be approximately 2500 ips to allow dependable recording of 21/2 megacycle signals, and the tape was to move at 30 ips.

In its early days, the project had a relatively low priority and in May of 1952 work on the videotape recorder was suspended for three months in favor of a crash project to turn out a one-of-its-kind instrumentation recorder. It turned out to be a fortunate interruption as it put me into very close contact with a 19 year old part-time engineering student by the name of Ray M. Dolby.

Although atthattime he had had noformal engineering training, his, technical understanding and ingenuity made him k key figure in the development program from the time of his first contact with it. Dolby dropped out of school to join the project when it was resumed in August of 1952 and was rewarded by losing his student draft deferment and being inducted in March of 1953.

We demonstrated an almost unrecognizable picture in October of '52, which was promising enough to maintain management's enthusiasm. We designed and built a second system that we had running in early March of '53. In this machine we used four heads mounted on the plane face of the drum instead of three in order to make use of a two-way switching system by which the output during playback of either of the two sets of diametrically opposed heads could be selected. The radius of the arc described by the rotating heads was about 1 Va inches, which permitted approximately 105 degrees of arc to be described by each head as it swept across the 2-inch wide tape.

An amplitude modulation system was used in which the video signal established the limiting amplitude in a clamp modulator. The capstan motor was driven directly from 60 cycle line frequency and the high speed drum motor was driven by a power amplifier whose input was the fifth harmonic of that signal. A photocell received the reflected light impulses from a lightsource that was focused on a rotating guard ring. The 300-cycle photocell drive signal was recorded on one edge of the tape by means of a conventional stationary head. During playback, the 300-cycle signal from the tape was used as the input signal to drive and control the drum power amplifier.

Although we were rather pleased by some aspects of the reproduced picture, the pleasure was attenuated close to the vanishing point by the number of unexpected problems confronting us.The pitfalls of the discontinuous method of recording were becoming painfully obvious. The odious label 'Venetian blinds" came into being to describe certain very unpleasant flaws at the points representing the crossover from one head to the next in the reproduced picture. The unsuitability of the method of control and the necessity for extreme accuracy in the positioning of the tape relative to the rotating heads became quite apparent and a good many hours devoted to analyzing the complexity of potential errors in the arcuate sweep geometry indicated that major revisions would be in order before the rotating head VTR could be successful.

By mutual consent, the project was shelved in June of 1953 in favor of certain high priority programs then in existence at Ampex. The understanding was that the subject of videotape recording would be revived within a few months in line with proposed solutions to several of the problems. Due to the pressure of other engineering needs of the company, the review did not come about as or when agreed.

Between June of 1953 and August of 1954 the videotape recorder had no continuous status, but a certain amount of progress had been made on specific problems by means of some very small man-hour and money allotments, some authorized and some bootlegged. Backed up by these advances, a report was submitted to management together with an urgent request for an 80-man-hour authorization to modify and demonstrate the revamped machine, which was known to us as the Mark I machine.

Receiving verbal notification that the authorization would come through, Charles E. Anderson and I changed the control system and demonstrated in August for a management committee. As a result, on September 1, 1954, the VTR program recommenced in earnest.

At the outset, there were two major technical changes. The first was a departure from arcuate sweep configuration to the geometry that became standard in the late '50s, in which the tape wrapped around the rotating drum and consequently the information was written across the tape in straight lines. The second was to be the development of an automatic gain control (AGC) system to compensate for all of the continuous as well as the step-function-type of amplitude fluctuations characteristic of the rotating head approach.

Late in September, Anderson, who was later to become the father of the FM system, Shelby Henderson, our model maker, and I were joined by Fred Pfost and in October by Alex Maxey. At the beginning of the new project, we had in our possession a total of six individual heads, four on the old drum and two spares. These heads were the first combination ferrite core and metal tip units made for video recording. They had been constructed a year and a half before, and although quite crude, they had worked at least well enough not to constitute any real limitation in the system performance during the early efforts.

Accordingly, in the Fall of 1954 we were not worried about duplicating the heads, assuming that once again some very simple jigs, some ferrite, metal tips, epoxy and elbow grease comprised the full complement of ingredients needed to duplicate them. Maxey was assigned to the task, which proved a severely aging experience for him. The problem was simply this. The new heads would not stay together under the high centrifugal force. The details of protective support holding the heads in place had been much more secure in the old configuration and we did not now have time to wait for an aging of the green epoxy. We reshaped the original composite heads in order to be abletousethem inthenewdrum. Itwasseveral months before we had the time.to go to an improved design.

In December of 1954, we made our first picture using the new geometry. The results were gratifying in terms of the improved stability, although it took a great deal of faith and understanding to be optimistic in the face of some rather gross shortcomings in the reproduced picture. The AGC system was not ready for use and it was beginning to be apparent that the problems facing it were extremely difficult.

The entire new head development program was carried by Pfost, wrio exhibited unbelievable tenacity and patience in coping with the all-important microcosms. Anyone who has attempted to wrest adequate response from magnetic heads at wavelengths below 200 microinches is well aware of the problems that were faced.

The modulation system was extended in bandwidth so that it would be suitable to operate with a carrier frequency of as high as six megacycles if such an operating frequency should subsequently turn out to be usable. The switching unit, which had previously been a two-mode device, was replaced by a four-way switcher that would allow only one channel at a time to conduct.

We made considerable improvements in resolution and in signal-to-noise ratio. We stabilized the drum sufficiently to allow the display of pictures from tape on a standard monitor. We had been making no attempt during this period to design a dressed up machine and had merely built a rather crude looking wooden cabinet containing the top plate and a few electronic units which operated in conjunction with two partially full racks. At a very small showing that we gave for some officers of the firm toward the end of 1955, it was suggested that we should package more attractively what was going to be a very expensive machine.

Accordingly, Anderson designed the Mark IV console with its compact rack arrangement. It was also decided at this time that we should start thinking definitely in terms of a surprise demonstration at the "National Association of Radio and Television Broadcasters" (NARTB - später nur NAB) convention in Chicago in April of 1956.

In early February of 1956, we gave a demonstration for what was originally supposed to be a very small management group but turned out to be one attended by about 30 Ampex people. For all of us on the engineering project, this was the most dramatic demonstration we were to make.

The guests arrived, were seated, a few words were spoken to the effect that we would show them what we had produced, and the machine was then put in the playback mode and played back a program we had recorded an hour earlier.

We then announced that we would record a sequence and immediately play it back. We recorded for about two minutes, rewound and stopped the tape, and pushed the playback button. Completely silent up to this point, the entire group rose to its feet and shook the building with hand-clapping and shouting. The two engineers who had done more fighting between themselves than the rest of the engineering crew combined, shook hands and slapped each other on the back with tears streaming down their faces.

We had quite a few visitors during the next couple of weeks, including Bill Lodge of CBS, Frank Marx of ABC and representatives of the CBC and BBC. The visitors were all sworn to absolute secrecy and generally ushered in and out separately so that they would not see each other.

As a result of Lodge's visit, arrangements were made to use a demonstration model, the Mark IV machine, which had not yet been assembled, for a surprise showing to the annual CBS affiliates meeting that was to occur the day before the formal opening of the NARTB convention.

With about six weeks to go before the convention, working hours were extended considerably in order to complete the construction of the Mark IV unit and at the same time to continue development work so that the picture to be demonstrated in Chicago would be as good as CBS was expecting it to be. The activity became furious.

The administrative engineer for the now considerably enlarged group shed his business suit in favor of work shirt and jeans and spent most of his regular time plus nights and weekends modifying mounting brackets for the new Mark IV console, making cable assemblies, and building up redesigned electronic units.

A three year old idea of placing the switching transients in the horizontal blanking interval was rushed into hardware form as the blanking switcher and integrated into the basic system as a toggle switch option. An automatic rotary head degaussing system came into being to obviate the necessity of manually demagnetizing the video heads after a recording operation and prior to playback.

Meanwhile, it had been decided that Mark III, the machine used for the prior demonstrations in February, should be used for a press demonstration in Redwood City, California, on the same day that the NARTB showing was to start.

Therefore, while Mark III was being used for development work, barely leading the construction of Mark IV, it also had to be prepared for its press appearance. The true orphan of the project, the audio, which had been sadly neglected uptothis point, had to be made at least to approach professional standards.

There were many heroes during this period, but leading them all was Pfost. Fred experimented with the heads up to the morning before embarking for Chicago. He varied tip structure, core structure, core windings, gap spacing, guide setting, current setting and built new heads continuously.

He did an unbelievable amount of work during this period. In the last four weeks preceding the Chicago demonstration, Pfost put in an average of well over 100 hours per week.

At last Mark IV was broken down into many pieces and shipped to Chicago. Three days before the press demonstration, the Redwood City machine was in severe mechanical trouble. Those of us who were headed for Chicago took off, wishing the stay-at-homes good luck and trying notto think about their difficulties.

In spite of the subjectively good pictures demonstrated in April of 1956, a resume of the tasks that had to be covered before releasing the first machine for air use (auf Sendung gehen) reveals how shaky our ground actually was at the time.

Until then, neither manpower nor machine facilities nor technical advances were sufficient to properly evaluate magnetic tape for videotape recording use. And until we could rate the tape manufacturers' samples with comments much more informative than "fair output," "too many dropouts," or "doesn't wear well," there was not too much that could be accomplished toward getting really satisfactory tape.

The tape evaluation program consumed many hundreds of man hours and was the cause of severe headaches to the tape manufacturers, to us and to our early network customers. With a then-predicted head life of 100 hours, we could not continue to make heads in a tedious one-at-a-time fashion.

The many parameters in head construction, several of which had been varied madly in cut-and-try fashion in order to squeeze out a few more precious db of signal-to-noise ratio for the April 1956  demonstrations, had to be settled on and frozen in order to establish at least our own standards before the delivery of the first machines.
.

At the same time, head construction had to evolve into a semiproduction process rather than a handcrafting technique. A processing unit had to be designed and developed which would be capable of providing blanking and sync in the reproduce signal that were sufficiently free of noise to allow the signal to be handled without difficulty by conventional stabilizing amplifiers and clamps anywhere along the line of transmission.

The picture reproduced from tape had to be greatly improved over that shown in April with respect to noise, resolution, overshoot and ringing, and horizontal stability. The entire machine and all individual chassis had to be repackaged and tested.

The mechanical design details were endless. Our top plate components had to be not only reliable but completely interchangeable. And always the struggle for greater bandwidth and better signal-to-noise ratio.