Computer Architecture and Data Representation: Key Concepts and Instructions

Address

location in a storage device.

Decimal point

period or comma in the decimal numbering system that separates the whole number from the fractional parts of a numbering system.

Floating point notation

method of encoding real numbers in a bit string consisting of two parts - mantissa and exponent.

String

ordered set of related data elements, usually stored as a list or a character array.

Two's complement notation

a system that represents positive integers as an ordinary bit string, and negative integers by adding one to the bit string that represents the absolute value.

Bit

value represented by in one position of a binary number. Number can have the value of zero or one.

Base

multiplier that describes the difference between one position and the next in a numbering system.

EBCDIC

Extended Binary Coded Decimal Interchange Code - IBM Mainframe coding standard for representing character data in an 8-bit format.

Range

set of all data values that can be represented by a specific data-encoding method.

Record

primary component data structure of a file relating to a single entity such as a person or transaction.

Radix

base of a numbering system, such as 2 for the binary numbering system and 10 for the decimal numbering system.

Unicode

standard 16-bit character coding method.

Single linked list

data structure in which each data item contains a pointer to the next data item.

Character

one byte of ASCII-encoded data or two bytes of Unicode-encoded data.

Pointer

data element that contains the address of another data element.

Data structure

a data item, such as an array or linked list, that contains multiple primitive data elements or other data structures.

Real number

number that can contain whole and fractional components.

Overflow

error condition that occurs when the output bit string of a processing operation is too large to fit in the designated registers.

Boolean logic

formal logic system in which data inputs and outputs can have only the values of true or false.

Index

stored set of paired data items. Each pair contains a key value and a pointer to the location of the data item possessing that key value.

Integer

whole number, or a value that does not have a fractional part.

Underflow

condition that occurs when a value is too small to represent in floating point notation.

Method

program within a class that manipulates data.

Byte

string of eight bits.

ASCII

stands for American Standard Code for Information Interchange - represents data using either 7 or 8 bits.

Doubly linked list

set of stored data items in which each element contains pointers to both the previous and next list elements.

Class

data structure that contains both traditional data elements and the software that manipulates the data elements.

ADD instruction

accepts two numeric inputs and produces their arithmetic sum.

AND instruction

generates the result of true if both of its data inputs are true. Generates the result of false if one or both of its data inputs are false.

Arithmetic Shift instruction

performs multiplication or division. Shifting to the left by one bit multiplies the value by two. Shifting to the right by one bit divides the value by two.

Benchmark

a measure of CPU or computer system performance when executing one or more specific tasks.

Branch operations

A branch instruction causes the processor to depart from sequential instruction order.

Clock cycle

each tick of the clock starts a new clock cycle.

Clock rate

the frequency at which the system clock generates timing pulses.

Complex Instruction Set Computing (CISC)

processor architecture that uses complex instructions that embed many primitive processing operations, in contrast to RISC.

Conditional Branch

occurs only if a specified condition is met, such as the equivalence of two numeric variables.

Conductivity

Electrical current is the flow of electrons from one place or device to another through conductors.

Data structure

A related group of primitive data elements organized for some type of common processing and is defined and manipulated in software.

Execution cycle

addition, subtraction or another data transformation takes place, and the data output is stored.

Exclusive XOR instruction

generates the value of true if one of the data inputs are true. Generates the value of false if both data inputs are true or if both data inputs are false.

Fetch cycle

data inputs are prepared for transformation into data outputs. Instruction moved from primary storage to the control unit.

GigaHertz

billions of cycles per second.

Heat sink

an object specifically designed to absorb heat and rapidly dissipate the heat via air or water movement.

Hertz

corresponds to one clock cycle per second.

Inclusive OR instruction

generates the value true if either or both data inputs are true. Generates the value of false if both data inputs are false.

Instruction

command to the CPU to perform one of its primitive processing functions on specific data inputs. An instruction is made up of an opcode and one or more operands.

Instruction format

a template that specifies the number of operands and the position and length of the op code and operands.

Instruction pointer (program counter)

stores the address of the instruction retrieved by the control unit. The instruction pointer is incremented by the control unit either during or immediately after each fetch cycle.

Instruction register

a special-purpose register that stores the instruction that the control unit fetches from memory.

Instruction Set

the collection of instructions that a CPU can process.

Integrated Circuit

several transistors and their interconnections are placed on a single chip.

Load operation

data transfer from main memory into a register.

Microprocessor

a microchip that contains all the circuits and connections that implement a CPU.

Millions of Floating point Operations Per Second (MFLOPS)

CPU performance when manipulating single precision floating point number.

Millions of Instructions Per Second (MIPS)

measure CPU performance when manipulating single precision integers.

MOVE instruction

copies data bits to storage locations.

Multiprocessing

any CPU architecture in which duplicate CPUs or processor stages can execute in parallel.

NOT instruction

transforms the Boolean value true into false.

Opcode

a unique binary number of the instruction.

Operand

input values for the instruction.

Pipelining

a method of organizing CPU circuitry to enable multiple instructions to be in different stages of execution at the same time.

Program Status Word

contains data that describes the status of the CPU and the currently executing program.

Reduced Instruction Set Computing (RISC)

a processor without complex instructions from the instruction set. The processor avoids instructions that combine data transformation and data movement operations.

Resistance

the loss of electrical power that occurs within a conductor.

Sequence control operations

alter the flow of instruction execution in a program.

Shift instruction

bit strings can be shifted to the right or left, the number of positions shifted may be greater than one.

Special-purpose registers

used by the CPU for specific purposes.

System Clock

a digital clock that generates timing pulses, or signals, and transmits the pulses to other devices within the computer.

Unconditional Branch

the processor always departs from the normal execution sequence.

Variable length instruction

the amount by which the instruction pointer is incremented after the fetch is the length of the most recently fetched instruction.

Wait state

each clock cycle that the CPU spends waiting for a slower device.

Word

a unit of data that contains a fixed number of bytes or bits. A CPU with a large word size can process faster than a CPU with a smaller word size.

Quiz - Cycle time

The cycle time of a processor is 1 divided by the clock rate (in Hz).

Quiz - Instruction formats

A CPU typically uses multiple instruction formats to account for differences in the number and type of operands in instructions.

Quiz - Resistance

Resistance generates heat in electrical devices.

Quiz - Gallium arsenide

Gallium arsenide is a semiconducting material with optical properties.

Quiz - Transistor

A transistor is an electrical switch built of semiconducting materials.

Quiz - Heat sink

A heat sink improves heat dissipation by providing a thermal mass and a large thermal transfer surface.

Quiz - Hertz

One hertz (Hz) is one cycle per second.

Quiz - Inclusive/Exclusive OR

Applying an inclusive OR transformation to input bit values 1 and 1 generates true. Applying an exclusive OR transformation to the same inputs generates false.

Quiz - Instruction register and decode

When an instruction is first fetched from memory, it's placed in the instruction register and then decoded to extract its components.

Quiz - Fixed-length instructions

Using fixed-length instructions simplifies the process of instruction fetching and decoding.

Quiz - Microprocessor

A microchip containing all the components of a CPU is called a microprocessor.

Quiz - OR instruction

An (inclusive) OR instruction transforms the bit pairs 1/1, 1/0, and 0/1 into 1.