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Author Maurer, Ward Douglas
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Copyright Year ©1966
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Abstract A computer is a set $\textit{M}$ (the memory), a set $\textit{B},$ a class of maps $\textit{S}:$ $\textit{M}$ → $\textit{B},$ known as states, and a class @@@@ of maps $\textit{T}:$ @@@@ → @@@@, known as instructions. Each instruction $\textit{I}$ has an input region $\textit{IR}(\textit{I}),$ an output region $\textit{OR}(\textit{I}),$ and affected regions $\textit{AR}(\textit{M′},$ $\textit{I}),$ for $\textit{M′}$ ⊆ $\textit{IR}(\textit{I}).$ For example, let $\textit{I}$ be the instruction (CLA Y) on the IBM 7094. If $\textit{L}$ is the location counter and $\textit{AC}$ is the accumulator, then $\textit{IR}(\textit{I})$ = $\textit{Y}$ ∪ $\textit{L}$ and $\textit{OR}(\textit{I})$ = $\textit{AC}$ ∪ $\textit{L};$ if $\textit{M′}$ is the address portion of $\textit{Y},$ then $\textit{AR}(\textit{M′},$ $\textit{I})$ is the address portion of $\textit{AC}.$ The fundamental properties of all these notions are derived, and computers are related to other models, such as sequential machines. The existence problem (how arbitrarily the input, output and affected regions of an instruction can be specified) is fully settled for countable memory $\textit{M}.$
ISSN 00045411
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 1966-04-01
Publisher Place New York
e-ISSN 1557735X
Journal Journal of the ACM (JACM)
Volume Number 13
Issue Number 2
Page Count 10
Starting Page 226
Ending Page 235


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Source: ACM Digital Library