1940 to 1949: Computing During World War II and the Postwar Era - The Technical and Social History of Software Engineering - page 69

ming, and many other fields. He published 150 scientific and mathematical papers
on many important topics.
It was von Neumann's seminal paper in 1945 titled “First Draft of a Report
on the EDVAC” that established the von Neumann architecture as the basis for
computer hardware design. However, another paper in 1945 by Alan Turing titled
“Automatic Computing Engine (ACE)” is remarkably similar to the von Neumann
report, and probably von Neumann had seen the Turing paper or knew of it.
The von Neumann architecture envisioned a digital computer as comprising a
processing unit for math and logic calculations, a control unit, internal memory
for storing both data and instructions, and a bus or channel for fetching data and
instructions as they were needed. There would also be external mass storage and
input/output mechanisms.
Although the von Neumann architecture has been visibly successful in hun-
dreds of computing machines, it had one feature that has been questioned. The von
Neumann architecture uses a single bus for both fetching data and instructions,
which limits performance. This is called the von Neumann bottleneck. Other ma-
chine architectures, such as the Harvard architecture, envisioned separate buses for
data and for instructions.
Future generations of researchers would also discover that the von Neumann
architecture might have security vulnerabilities that hackers could take advantage
of.
Another computer started during World War II was known as the Harvard
Mark I. The official name was the IBM Automatic Sequence Controlled Calculat-
or (ASCC). This was an electromechanical computer commissioned in 1943 and
constructed in 1944. The U.S. Navy's Bureau of Ships issued the contract.
The Harvard Mark I was designed by another famous computer pioneer,
Howard H. Aiken of Harvard. The computer itself was built at IBM in Endicott,
New York, and transferred to Harvard upon completion in 1944.
Another famous software pioneer who was also part of the Mark I design team
was Grace Hopper. She later became famous for the development of COBOL and
for becoming a U.S. Navy Admiral at the peak of her illustrious career.
Grace Hopper took a leave of absence from Vassar in 1943 and joined the
WAVES, which was the U.S. Navy organization for women personnel. At the time
of the Mark I project, her Navy rank was Lieutenant JG.