Chapter 5 Vocab

address space

The maximum amount of memory that a computer can physically hold; determined by the size of the address field

Arithmetic Logic Unit

computer subsystem that performs mathematical and logical operations such as addition, subtraction, and comparison for equality

bus

(1) a path for electrical signals; (2) LAN topology in which all nodes are connected to a single shared communication line

cache hit rate

The percentage of the time that the information needed is in cache memory

cache memory

A high-speed memory unit that keeps a copy of memory cells with a high likelihood of access in the near future

Central Processing Unit

The part of the computer consisting of the control unit and the ALU

CISC machine

Complex Instruction Set Computer; a machine that has a very large and complex instruction set

cluster computing

independent systems, such as mainframes, desktops, or laptops, are interconnected by a local area network (LAN) like the Ethernet or a wide area network (WAN) such as the Internet; also called MIMD parallel processing

Computer Organization

the branch of computer science that studies computers in terms of their major functional units and how they work

control unit

The computer subsystem that fetches and executes instructions stored in the memory of the computer

data path

The ALU circuits, registers, and interconnections between components

destructive store

When you store a new value in a memory cell and destroy its previous contents

direct access storage devices

A mass storage device in which each unit of information is associated with a unique address, but the time to access each piece of information may not be the same

fetch/store controller

The component that determines whether a value will be placed into memory or copied from memory

functional units

Subunits of a computer that perform tasks such as instruction processing, information storage, computation, and data transfer

grid computing

A MIMD model in which the individual processors can be computer systems belonging to a wide range of groups or individuals

Hierarchy of Abstractions

A series of abstractions, each one more detailed and each one showing lower level components of a system

I/O controller

A special-purpose device that controls the operations of an input/output device

input/output

The devices that allow a computer system to communicate and interact with the outside world, as well as to store information

instruction register

The register that holds a copy of the instruction to be executed

instruction set

set of all operations that can be executed by a processor

interrupt signal

A signal sent by the I/O controller to the CPU to let it know that it has completed an I/O operation

latency

The time required to rotate the disk to the beginning of the desired sector

level of abstraction

An alternate perspective or a different way to view a system

machine language

The programming language that a processor is able to directly understand and execute; written in binary

mass storage systems

Systems or devices where information is kept for long periods of time and not lost when the computer is not being used

memory

Th functional unit of a computer that stores and retrieves instructions and data being executed

memory access time

The time it takes to fetch or store the contents of a single memory cell

memory address

The unique numeric identifier for a memory cell

Memory Address Register

The memory register that holds the address of the cell to be fetched from or stored into

memory cell

The minimum unit of memory access

Memory Data Register

The memory register that holds the data value to be stored or the data value that was just fetched

memory width

The number of bits in a single memory cell

MIMD parallel processing

multiple instruction stream/multiple data stream; a parallel processing model in which multiple processors all work independently on their own program to solve a single problem; also called cluster computing

nanosecond

one billionth of a second

non-destructive fetch

When you access the contents of a memory cell and copy it, but do not destroy it

Non-Von Neumann architecture

Computer designs based on models other than the standard Von Neumann architecture

nonvolatile memory

Memory that does not lose its contents even when the power is turned off

parallel algorithms

Algorithms that exploit the presence of multiple processors to solve a single problem

parallel processing

Building computers with two or more processors that work in parallel

principle of locality

When you access a memory cell, it is likely that you will also access memory cells nearby very soon

processor

A system that is composed of the ALU together with the control unit

program counter

A register that holds the address of the next instruction to be executed

quantum computing

A field of computer design using the principles of quantum mechanics in which a single bit of information can be not just a 0 or a 1 but in both states at the same time.

Random Access Memory

A memory structure in which each cell has an address and it takes the same amount of time to fetch or store any cell

read-only memory

A memory structure that can only be accessed, not written into or changed

register

A special, high-speed storage cell

RISC Machine

Reduced Instruction Set Computer; a machine that has a very small and simple instruction set, but where each instruction is highly optimized and executes very quickly

sector

A disk storage unit containing an address, a data block, and a fixed number of bytes; sectors are arranged in concentric tracks on a disk

seek time

The time required to move the read/write head to the correct track

sequential access storage device

A mass storage device in which information is located by sequentially searching all the information that is stored

sequential execution

One instruction at a time is fetched from memory to the control unit, where it is decoded and executed

SIMD parallel processing

single instruction stream/multiple data stream; a parallel processing model in which multiple processors all execute the same instruction on their own local data

stored program

The instructions to be executed by the computer are represented as binary values and stored in memory

track

A single concentric circle of information on a disk

transfer time

The time required to read the desired sector into main memory.

vector

an ordered collection of values

volatile memory

Memory that loses its contents when the power is turned off

Von Neumann Architecture

The computational model designed by John Von Neumann and first implemented in the EDSAC computer of 1947; the structure and organization of virtually all modern computers

Von Neumann bottleneck

The inability of sequential, one-at-a-time processors to handle extremely large problems in a reasonable time scale