[PRELIMS] CS003 Computer Architecture

Number Systems

Decimal, Binary, Octal, and Hexadecimal are the major number systems discussed in the module.

Decimal Number System

A base-10 positional number system using the digits 0–9.

Binary Number System

A base-2 number system using only 0 and 1.

Octal Number System

A base-8 positional number system using the digits 0–7.

Hexadecimal Number System

A base-16 positional number system using 0–9 and A–F.

Bit

A single binary digit, either 0 or 1.

Least Significant Bit (LSB)

The rightmost digit in a binary number.

Most Significant Bit (MSB)

The leftmost digit in a binary number.

Positional Value System

A number system where the value of a digit depends on its position.

Byte

A unit consisting of 8 bits.

Kilobyte (KB)

1024 bytes.

Megabyte (MB)

1024 KB.

Gigabyte (GB)

1024 MB.

Terabyte (TB)

1024 GB.

Petabyte (PB)

1024 TB.

Exabyte (EB)

1024 PB.

Zettabyte (ZB)

1024 EB.

Yottabyte (YB)

1024 ZB.

Character Encoding

Methods used to represent characters and symbols using numeric or binary codes.

Alphanumeric Codes

Codes used to represent letters, digits, punctuation marks, mathematical operators, and special symbols.

ASCII - American Standard Code for Information Interchange

a widely used alphanumeric code.

ASCII Bit Size

ASCII is described in the module as a 7-bit code with 128 possible codes.

ISCII - Indian Script Code for Information Interchange;

developed to support Indian languages on computers.

Unicode

An international coding system that provides a unique number for every character regardless of platform, program, or language.

Data Representation

The form in which data is stored, processed, and transmitted.

Representing Text

Representing each character using a unique fixed-length sequence of bits.

Pixel

A small picture element used to construct a digital image.

Bitmap

A collection of encoded pixels representing an image.

RGB Color Model

A color model using red, green, and blue light to represent a wide spectrum of colors.

GIF - Graphic Interchange Format

; a compression method that reduces bitmap size by limiting colors assigned to a pixel to 256.

JPEG - Joint Photographic Experts Group;

a commonly used method for compressing photographs.

IEEE 754

The IEEE standard for floating-point arithmetic and the common representation of real numbers on computers.

IEEE 754 Components

Sign, biased exponent, and normalized mantissa.

Sign Bit

The IEEE 754 bit where 0 represents a positive number and 1 represents a negative number.

Biased Exponent

The exponent stored after adding a bias to the actual exponent.

Normalized Mantissa

The significant part of a floating-point number represented with only one 1 to the left of the binary point.

Single Precision

IEEE 754 format using 1 sign bit, 8 exponent bits, and 23 mantissa bits with a bias of 127.

Double Precision

IEEE 754 format using 1 sign bit, 11 exponent bits, and 52 mantissa bits with a bias of 1023.

Single Precision Bias

The bias value of 127 used in IEEE 754 single precision.

Double Precision Bias

The bias value of 1023 used in IEEE 754 double precision.

Zero

A special IEEE 754 value represented with an exponent and mantissa of 0.

Denormalized Number

A number with an all-zero exponent and a nonzero mantissa, without an assumed leading 1.

Infinity

An IEEE 754 special value represented by an all-one exponent and all-zero mantissa.

NaN

Not A Number; an IEEE 754 value used to represent an error or undefined value.

Overflow

A condition where a value becomes too large to be represented.

Underflow

A condition involving values too small to be represented accurately, resulting in loss of precision.

Floating-Point Conversion Steps

Determine sign, convert whole and fractional parts to binary, normalize, determine biased exponent, obtain mantissa, and combine the fields.

Computer Organization

The physical aspects of computer systems, such as circuit design, control signals, and memory types.

Computer Architecture

The logical aspects of system implementation as seen by the programmer, such as instruction sets, formats, data types, and addressing modes.

Principle of Equivalence of Hardware and Software

The principle that any task performed by software can also be performed by hardware and vice versa, assuming speed is not a concern.

Computer Components

Processor, memory, and a mechanism for transferring data to and from the outside world.

Processor

A component that interprets and executes programs.

Memory

A component used to store data and programs.

Input/Output Mechanism

A mechanism for transferring data to and from the outside world.

Input Unit

The part of the computer consisting of devices that input data into the computer.

Input Devices

Devices such as keyboard, mouse, scanner, digital camera, microphone, QR code reader, and RFID reader used to enter data.

Memory Unit

The part of the computer responsible for storing programs and data.

RAM

main memory where programs are stored during execution and which is erased when the computer is turned off.

ROM

memory containing special instructions needed for the computer to operate.

Cache Memory

A temporary memory that increases processor speed by recording and anticipating instructions.

Secondary Storage

Storage provided by peripheral devices for storing large amounts of data more permanently.

Processing Unit

The part of the computer responsible for processing data and instructions.

CPU

the brain of the computer containing circuitry needed to process input, store data, and output results.

ALU

performs arithmetic and logic operations and manipulation of numbers.

Control Unit (CU)

The component that controls and coordinates the order and execution of program instructions.

Output Unit

The part of the computer consisting of devices used to communicate data from the computer to users.

Output Devices

Devices such as display screens, printers, and headphones used to communicate results to users.

Capacity and Speed Measures

Kilo, Mega, Giga, Tera, Peta, Exa, Zetta, Yotta, Hertz, and Byte are measures discussed in the module.

Kilo (K)

1 thousand; 10³ or 2¹⁰.

Mega (M)

1 million; 10⁶ or 2²⁰.

Giga (G)

1 billion; 10⁹ or 2³⁰.

Tera (T)

1 trillion; 10¹² or 2⁴⁰.

Peta (P)

1 quadrillion; 10¹⁵ or 2⁵⁰.

Exa (E)

1 quintillion; 10¹⁸ or 2⁶⁰.

Zetta (Z)

1 sextillion; 10²¹ or 2⁷⁰.

Yotta (Y)

1 septillion; 10²⁴ or 2⁸⁰.

Hertz

A measure of clock cycles per second or frequency.

Byte

A unit of storage.

Millisecond

One thousandth of a second.

Microsecond

One millionth of a second.

Nanosecond

One billionth of a second.

Picosecond

One trillionth of a second.

Femtosecond

One quadrillionth of a second.

Attosecond

One quintillionth of a second.

Zeptosecond

One sextillionth of a second.

Yoctosecond

One septillionth of a second.

Micron (Micrometer)

One millionth of a meter.

Cycle Time

The reciprocal of clock frequency.

System Bus

A bus that moves data within the computer.

L1 Cache

Level 1 cache; smaller and generally faster than L2 cache.

L2 Cache

Level 2 cache; larger and generally slower than L1 cache.

ATA - Advanced Technology Attachment

; describes how the hard disk interfaces with other system components.

Port

A connection that allows movement of data between a system and its external devices.

Serial Port

A port that sends data as a series of pulses along one or two data lines.

Parallel Port

A port that sends data as a single pulse along at least eight data lines.

USB - Universal Serial Bus

; an intelligent serial interface that is self-configuring and supports plug-and-play.

PCI - Peripheral Component Interface

; a dedicated I/O bus that can augment system buses.

Refresh Rate

The number of times per second that an image on a monitor is repainted.

Dot Pitch

A measure that indicates how clear the image on a monitor is.

Video Card

A component containing memory and programs that support the monitor.