With support from the senior executives, a handful of IBM's population in Poughkeepsie, New York, set to work. "No single person came up with the idea of magnetic tape," according to Phelps. "It grew out of a number of meetings and discussions involving principally Gordon Roberts and Steve Dunwell of the 'Future Demands' department; W. W. McDowell, vice president of engineering; R. L. Palmer, manager of the Poughkeepsie Lab; and yours truly."
Magnetic recording was an unexplored topic in 1949, so much so that "stuff you can learn in a primer from Sam's Bookstore today, we didn't know" (Max Femmer, tape pioneer). As in most creative efforts, improvisation would play a role in the development of the magnetic tape drive. James Weidenhammer, a key figure in the invention of the vacuum column¹, stated, "We had no clear idea of which approach to take. Very fast starts and stops were desirable to minimize the wasted tape and read-write delays. With tape speeds anticipated to be 100 to 200 inches per second, it was obviously impractical to accelerate bulky tape storage reels rapidly enough. Storage loops or buggers would be necessary in the tape path for gradual acceleration of the reels." The vacuum column provided this loop of tape and allowed the early prototype to mimic punch card records.
Once the idea of the vacuum column was hit upon and the vacuum switch conceived, "We were in a hurry to try out the idea, wrote Weidenhammer, "and needed some very thin, flexible material to fabricate a sensitive pressure-sensing diaphragm. With nothing suitable on hand, the quickest solution that occurred to me was to send one of the young engineers, Jack Seely, to the nearest drug store for a pair of baby pants. They worked."
The vacuum pump, which was necessary to produce the vacuum in the columns, provided another challenge. Throughout development, the motor from an old General Electric vacuum cleaner was used. When the tape drive was released for production, that same motor was included because the prototype drives had been optimized for it. Dick Whalen, manager of procurement for the program, divulged, "It turned out that this was an obsolete vacuum cleaner. A GE sales rep searched warehouses all over the country to get us under way."
Winger recalled the confusion that resulted in the early days when magnetic tape was largely unknown, even within IBM: "We got a shipment of tape from our supplier and it was delivered to the receiving dock. The man in charge came over and said, 'We just got a shipment of tape from 3M, but we're going to have to send it all back because it doesn't have any glue on it!"
IBM pioneered not only the tape drives, but also the half-inch tape itself. Vic Witt, who retired as an IBM Fellow in 1980, played a large part in that program. "I started with the program in 1951," recalled Witt. "There were no tape experts at that time. They handed me a piece of tape and said, 'You have to know everything there is to know about this stuff.' It was quarter-inch, and we were going to use half-inch, but this was all we had then. We worked with 3M to find a way to produce tape to our specifications. We said, 'We need tape so flawless that if it were a highway stretching the 60-plus miles from Poughkeepsie to Manhattan, any defect would be the size of a marble."
A test center was built in Minnesota where all of the tape developed was inspected by an operator, who -- armed with a microscope and knife -- cut out any defects and sent it back to Poughkeepsie to be corrected. The cost for testing the tape was at least as much as manufacturing it.
IBM designed and built the world's most advanced tape coater in Poughkeepsie and the first "clean room" used in manufacturing. Witt explained, "No one had ever heard of keeping the air in a manufacturing plant that pure, but we had to have it if the tape was going to meet our specifications. We showed the world that it could be done."
IBM's first magnetic tape unit, the IBM 726, was announced in 1952 -- the year Thomas J. Watson Jr. became IBM president and the employee population passed 40,000. It was announced with the IBM 701 Defense Calculator, the company's first commercially marketed electronic computer. A development model was called the "Tape Processing Machine" by the engineers who designed and built it -- an indication of the pivotal role played by magnetic tape in launching the data processing industry.
The Wall Street Journal article on the day the 701 was announced said it was "designed to shatter the time barrier confronting technicians working on vital atomic and airplane projects." It went on to say that the first computer would be used to "calculate atomic radiation effects and to compute the many statistics that scientists need to know about planes, guided missiles and rocket engines."
The General Motors Research Laboratories used a 701 in the mid-1950s to solve engineering problems. One problem in stress analysis was evaluated for more than 100,000 variables. A GM publication noted at the time that "working 40 hours a week, 52 weeks a year with a desk calculator, an engineer would have taken 12 years to solve this problem. After allowing the mathematicians in data processing about a month to set up the problem, the 701 provided the required answers in 1.5 hours." As a GM employee noted, "Jobs once thought impossible are now attacked without hesitation."
On March 27, 1953, the New York Times reported that one chemical company planned to rent time on the 701 at IBM headquarters to solve a cost accounting problem. It would take about 100 hours of machine time to solve the problem while, according to an IBM spokesman at the time, it would take an accountant with a desk calculator 2,500 years.
The data processing industry's first half-inch magnetic tape drives, IBM 726 Tape Units, were shipped with the IBM 701 Defense Calculator from December 20, 1952 until February 28, 1955. Sixteen companies were willing to risk migrating their data from punch cards to the then-unproven magnetic tape.