Figure 1-6 Clifford Berry with the ABC (www.scl.ameslab.gov/ABC/Progress.html).
Computer (ABC) used only 300 vacuum tubes and was capable of performing arithmetic electronically.
Perhaps what is most important about this particular machine is that is operated on base-2 numbers (binary).
The ABC did not implement the stored program idea, however, so it was not a general-purpose
computer.
During the same time period, Howard Aiken was working on the Mark I computer at Harvard University.
As completed in 1944, the Mark I contained more than 750,000 parts, including switches, relays, rotating shafts,
and clutches. The machine was huge, at 51 feet long, 8 feet high, 2 feet thick, and weighing 5 tons. It had 500
miles of wiring, and three million wire connections. The machine sounded like a ???roomful of ladies knitting???
when it was running. Aiken showed that it was possible to build a large-scale automatic computer capable of
reliably executing a program.
CHAP. 1] INTRODUCTION TO COMPUTER SCIENCE 9
Figure 1-7 The Aiden/IBM Mark 1 Computer installed at Harvard, photograph IBM Corporate Archives.
One of the people who worked with Aiken on the Mark I was Grace Murray Hopper, a freshly commissioned
lieutenant in the US Naval Reserve.
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