ENIAC lacked stored‑program design, needed manual rewiring
Question asked:
“The original ENIAC computer did not have a stored-program architecture, and its instructions were physically built into the hardware configuration, requiring technicians to manually reconfigure switches, dials, and plugboard cables to change programs.”
Summary
The ENIAC did not use a stored‑program architecture; its instructions were implemented by physically wiring plugboards, setting switches, and adjusting dials. Changing a program required technicians to manually reconfigure these hardware elements for each new computation.
Sources 60 searched
- Hitting the Jackpot: The Birth of the Monte Carlo Method | LANL
Although construction of ENIAC ... be in demand for years. It was initially programmed by rewiring cables and setting switches on an enormous set of plugboard panels (Fig....
- ENIAC Programmers
The ENIAC was not a stored-program computer; it is "better described as a collection of electronic adding machines and other arithmetic units, which were originally controlled by a web of large electrical cables" (David Alan Grier, IEEE Annals of the History of Computing, Jul-Sep 2004, p.2).
- eniac's 50th Anniversary: The Birth of the Information Age -- A Short History of the Second American Revolution by Dilys Winegrad and Atsushi Akera
Eckert had proposed ways to overcome ... memory, for ENIAC could store only twenty numbers in high-speed memory. But the stored program would not be implemented till ENIAC's successor machines were built....
- An Illustrated History of Computers Part 4
To reprogram the ENIAC you had to rearrange the patch cords that you can observe on the left in the prior photo, and the settings of 3000 switches that you can observe on the right. To program a modern computer, you type out a program with statements like:
- Penn’s ENIAC, the world’s first electronic computer, turns 80 | Penn Today
Because ENIAC lacked internal program storage, the programmers had to configure each computation manually. They stood between the machine’s 30-ton panels, rewiring plugboards and setting switches to route electric signals (pulses).
- The world’s first general purpose computer turns 75 | Penn Today
Designed by John Mauchly and J. Presper Eckert, ENIAC was the fastest computational device of its time, able to do 5,000 additions per second, but because it had no internal storage, it had to be programmed manually for each new set of calculations.
- The Eniac and Pi | Wittenberg University
However, the experience with the ... project, the EDVAC (the Electronic Discrete Variable Automatic Computer) which unlike the ENIAC was a true modern computer in that both code and data were stored in its internal memory...
- ENIAC - Wikipedia
A number of improvements were made ... stored programming mechanism using the function tables as program ROM, after which programming was done by setting the switches. The idea has been worked out in several variants by Richard Clippinger and his group, on the one hand, and the Goldstines, on the other, and it was included in the ENIAC patent. Clippinger consulted with von Neumann on what instruction set to implement. Clippinger had thought of a three-address architecture while von ...
- Programming the ENIAC: an example of why computer history is hard - CHM
ENIAC’s April feat was an accomplishment, but there’s at least one good reason why calling it a “first” is problematical: the program was stored in what we now call “read-only memory”, or ROM.
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