Mind, Body, World- Foundations of Cognitive Science, 2013a

predefined value was reached (Williams, 1997). The switches would route incoming
signals to particular components of ENIAC, where computations were performed;
a change in a switch’s state would send information to a different component of
ENIAC. The control of this information flow was accomplished by using a plug
board to physically wire the connections between switches and computer components.
This permitted control to match the speed of computation, but at a cost:
ENIAC was a fast but relatively inflexible machine. It was best suited for use in
long and repetitious calculations. Once it was wired up for a particular program,
it was in fact a special purpose machine. Adapting it to another purpose (a different
problem) required manual intervention to reconfigure the electrical circuits.
(Pelaez, 1999, p. 361)
Typically two full days of rewiring the plug board were required to convert ENIAC
from one special purpose machine to another.
Thus the development of electronic computers led to a crisis of control. Punched
tape provided flexible, easily changed, control. However, punched tape readers were
too slow to take practical advantage of the speed of the new machines. Plug boards
provided control that matched the speed of the new componentry, but was inflexible
and time consuming to change. This crisis of control inspired another innovation,
the stored program computer (Aspray, 1982; Ceruzzi, 1997; Pelaez, 1999).
The notion of the stored program computer was first laid out in 1945 by
John von Neumann in a draft memo that described the properties of the EDVAC
(Electronic Discrete Variable Automatic Computer), the computer that directly
descended from the ENIAC (Godfrey & Hendry, 1993; von Neumann, 1993). One of
the innovations of this design was the inclusion of a central controller. In essence,
the instructions that ordinarily would be represented as a sequence on a punched
tape would instead be represented internally in EDVAC’s memory. The central
controller had the task of fetching, interpreting, and executing an instruction from
memory and then repeating this process after proceeding to the next instruction
in the sequence.
There is no clear agreement about which particular device was the first stored
program computer; several candidate machines were created in the same era. These
include the EDVAC (created 1945–1950) (Reitwiesner, 1997; von Neumann, 1993;
Williams, 1993), Princeton’s IAS computer (created 1946–1951) (Burks, 2002;
Cohen, 1999), and the Manchester machine (running in 1948) (Copeland, 2011;
Lavington, 1980). Later work on the ENIAC also explored its use of stored programs
(Neukom, 2006). Regardless of “firsts,” all of these machines were functionally
equivalent in the sense that they replaced external control—as by a punched
tape—with internalizing tape instructions into memory.
The invention of the stored program computer led directly to computer science’s
version of the classical sandwich (Hurley, 2001). “Sensing” involves loading
Marks of the Classical? 329