final book al hoagland - Archive Server - Computer History Museum

against wear by using air pressure with nozzles in the face of the flat head. The
airflow spaced the head a uniform distance from the sometimes wobbly disks. Air
pressure was also used to force the head toward the disk after it reached its destination.
Stored bit density at the center tracks was made the same as the state of the art
density in magnetic drums, 100 bits to the inch and 20 tracks to the inch. This was
better than a 4,000% improvement over punched cards in information density and the
data was alterable and erasable.
In our first file model two-foot diameter oxide-coated disks were mounted on a
horizontal shaft at ½-inch intervals. Fifty-one disks gave 100 inside surfaces. Two
opposite facing heads were mounted on one access arm. The access arm was moved so
as to place the heads on any of the 100 tracks on each of the 100 disk surfaces at a
speed that would match an accounting machine cycle, which was less than one
second. We had anticipated that there would be a need for as many as six access
stations on each file. Given positioning tolerances, even with two actuators the access
positioning of each was limited to the top or bottom half of the disk stack The
maximum travel between addresses was one-twentieth of an inch.
Two access drive systems were designed and modeled, one mechanical and one
electronic-servo system. We finally chose an electronic-servo system for the first file
model.
The tub file application led us to test out the disk performance by pairing it with
a keypunch, because the keypunch could be used for entering information and for
recording in punched holes the information read back from the disk file.
On February 10, 1954, this first sentence was fed into and read back from the
disk file – “This has been a day of solid achievement.”
By March 1954, tests of components and the card to file machine made us
confident of being able to build a product. Lou Stevens was made the manager with
full development responsibility.
He and his staff of very capable engineers initiated a program of re-design that
started in mid-March 1954. By November this design had matured into a “magnetic
disk processing machine.” RAMAC was on its way. Hopes were high that this
revolutionary concept would develop into an IBM product.
The potential for large random access memory was attested to be activity among
competitors who were using very large drums, drum arrays, tape loops and even the
surface of a power station fly wheel as recording surfaces.
The IBM vice-president for marketing, L.H. LaMotte, stationed his long-range
planner, F.J. Wesley, in our laboratory mid-summer, 1954. On October 8, 1954, Mr.
Wesley sent a memorandum, which he called a “pontifical announcement,” to his
boss. In part it started, “we must immediately attack accounting problems under the
philosophy of handling each business transaction as it occurs, rather than using
batching techniques.” Wesley’s memo was widely circulated among IBM management
and, needless to say, in our laboratory. The promise of developing a product for more
than a file tub replacement led to a corporate decision in November 1954 to build at
least five prototypes of our product to field test.
Initial specifications for the RAMAC were prepared December 17, 1954.
The non-RAMAC projects of the research and engineering laboratory moved to
Julian Street to open more spaces for the RAMAC team. At the Julian Street
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