On-Line Data-Acquisition Systems in Nuclear Physics, 1969: Chapter 1 - THE COMPUTERS

On-Line Data-Acquisition Systems in Nuclear Physics, 1969, by H. W. Fulbright et al. National Research Council is part of the HackerNoon Books Series. You can jump to any chapter in this book here. Chapter 1: THE COMPUTERS

C. THE COMPUTERS

1. Introduction

Because computers have proved useful in so many fields, many varieties are now on the market, quite a few of them having properties highly suitable for nuclear-data acquisition. The properties particularly useful are, first, the ease with which a great variety of external input and output devices can be attached (interfaced to the computer); second, provisions for rapid, efficient response to interrupt signals from external devices; and third, usually a means of transferring data from external devices directly into blocks of memory without use of the central processor, the transfer possibly requiring only a single memory cycle per word. (This is referred to as direct memory access through a direct data channel.)

Several types of small computers have appeared on the market during the past year, some having 8-bit words, but they are too small for general data-acquisition use, although valuables for special applications. For present purposes, the smallest useful machines have a minimum memory size of 4096 (4k) 12-bit words, which can usually be enlarged to 32k words by the addition of memory modules, while the larger machines have minimum memories of at least 8k, with provision for expansion to several hundred k. Regardless of their size, the machines of the present generation all have memory cycle times around 1 or 2 µsec.

2. Rough Classification of Computers

Before proceeding with the discussion it is convenient to find a simple scheme for classifying computers. The scheme adopted here is to divide them into three loosely defined classes—small, medium, and large—essentially on the basis of the properties of the basic central processors:

Small
Word length 12 to 18 bits
Useful memory size 4k
Number of bits in instruction 3 or 4
Floating-point hardware orally offered
Approximate cost range $8500 to $40,000

Medium
Word length 16 to 24 bits
Useful memory size 8 to 16k
Number of bits in instruction 4 to 6
Floating-point hardware option sometimes offered
Approximate cost range $30,000 to $120,000

Large
Word length 32 to 48 bits
Useful memory size at least 16k
Number of bits in instruction 7 or more
Floating-point hardware
Approximate cost range $150,000 or more

Computers do not fall neatly into these three classifications, especially since manufacturers offer many optional features; therefore, some argument about the assignment of a particular machine to one or the other class is possible. This is especially true with respect to the small and medium types. The properties of a large number of small and medium-sized computers are given in Appendix A. Information on larger machines can be found in the Adams Associates Computer Characteristics Quarterly.

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H. W., Fulbright et al. 2013. On-Line Data-Acquisition Systems in Nuclear Physics, 1969. Urbana, Illinois: Project Gutenberg. Retrieved May 2022 from https://www.gutenberg.org/files/42613/42613-h/42613-h.htm#Page_3

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