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Exploring the Architecture of an Early Machine: The Historical Relevance of the ENIAC Machine Architecture

IP.com Disclosure Number: IPCOM000129914D
Original Publication Date: 1996-Apr-30
Included in the Prior Art Database: 2005-Oct-07
Document File: 13 page(s) / 53K

Publishing Venue

Software Patent Institute

Related People

MITCHELL MARCUS: AUTHOR [+3]

Abstract

Although many historians and enthusiasts alike have written about the history of the ENIAC, very few scholars have considered the detailed aspects of the ENIAC design. This should come as no surprise; the fact that the ENIAC had over 30 units with a total of 17,480 vacuum tubes alone makes it seem a daunting task to try to understand this machine. Furthermore, since the ENIAC was one of the first large scale electronic computers, and more significantly, a crucial machine that convinced so many people -- scientists, military officials, and industrialists alike -- to commit to the rapid development of electronic computing, the uniqueness of its architecture was lost in the tumultuous efforts that followed. In other words, the many efforts devoted to improving machine architectures after the ENIAC drowned out much of the technical contributions that were part of the ENIAC; it also hid the various limitations of the machine. Indeed, the ENIAC was neither fish nor fowl. While carrying many of the vestiges of earlier calculating machines, it had gone beyond simple calculations to permit a more flexible mode of operation, conditional branching, and a very limited, but high speed storage of intermediate data. But the vestiges were not simply in the area of hardware. The ENIAC, though a general purpose computer, was designed to carry out high speed computations of differential equations, which was the heritage both of earlier learning in elementary numerical analysis, as well as the more immediate class of problems that were also being solved by differential analyzers -- although the particular method employed, that of numerical integration, differed from the fundamental operating principle of the differential analyzers. These are but some of the basic observations about the ENIAC architecture that we feel are relevant both for historical and current technical inquiries. We begin here by presenting some general historical details that are relevant to the present inquiry. Following this historiographical section will be a more intensely technical history which, we hope, will nonetheless help historians to rediscover a certain feel for research traditions and other aspects of historical context that might otherwise be difficult to recover from more traditional historical sources.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Copyright ©; 1996 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Used with permission.

Exploring the Architecture of an Early Machine: The Historical Relevance of the ENIAC Machine Architecture

MITCHELL MARCUS

ATSUSHI AKERA

After presenting the historiographical background to the ENIAC development, this paper examines the technical history of the machine. The technical section looks at the architecture of the Accumulators and the Master Programmer Unit in an attempt to illustrate both the advantages and the shortcomings of the design. In particular a description of a conditional branch mechanism and parallel operations are provided -- together with a discussion of reasons why they were not used in any extensive way.

Introduction

Although many historians and enthusiasts alike have written about the history of the ENIAC, very few scholars have considered the detailed aspects of the ENIAC design. This should come as no surprise; the fact that the ENIAC had over 30 units with a total of 17,480 vacuum tubes alone makes it seem a daunting task to try to understand this machine. Furthermore, since the ENIAC was one of the first large scale electronic computers, and more significantly, a crucial machine that convinced so many people -- scientists, military officials, and industrialists alike -- to commit to the rapid development of electronic computing, the uniqueness of its architecture was lost in the tumultuous efforts that followed. In other words, the many efforts devoted to improving machine architectures after the ENIAC drowned out much of the technical contributions that were part of the ENIAC; it also hid the various limitations of the machine.

Indeed, the ENIAC was neither fish nor fowl. While carrying many of the vestiges of earlier calculating machines, it had gone beyond simple calculations to permit a more flexible mode of operation, conditional branching, and a very limited, but high speed storage of intermediate data. But the vestiges were not simply in the area of hardware. The ENIAC, though a general purpose computer, was designed to carry out high speed computations of differential equations, which was the heritage both of earlier learning in elementary numerical analysis, as well as the more immediate class of problems that were also being solved by differential analyzers -- although the particular method employed, that of numerical integration, differed from the fundamental operating principle of the differential analyzers. These are but some of the basic observations about the ENIAC architecture that we feel are relevant both for historical and current technical inquiries.

We begin here by presenting some general historical details that are relevant to the present inquiry. Following this historiographical section will be a more intensely technical history which, we hope, will nonetheless help historians to rediscover...