Parallel Computing

Serial Computing

A computer typified by bit-serial architecture; processes data one bit at a time.

Parallel Computing

A type of computation in which many processes are carried out simultaneously, often using multiple processors.

Serial Computing

A computer typified by bit-serial architecture; processes data one bit at a time.

Parallel Computing

A type of computation in which many processes are carried out simultaneously, often using multiple processors.

1-bit computer instructions

Operate on data consisting of single bits.

Computer architecture

Defines the functionality, organization, and implementation of a computer system.

The Processor

One of the most essential components in the computer system; executes instructions and completes tasks assigned to it.

An Operating System

Executes many programs, each of which has multiple tasks.

Serial Algorithm

An algorithm that is executed sequentially from start to finish without other processing executing.

Serial Processing (Sequential Processing)

One task at a time; after completing a task, it sequentially executes other tasks.

Parallel Processing

Multiple processors execute tasks simultaneously; increases throughput and improves reliability.

Electronic Discrete Variable Automatic Computer EDVAC

(1949).

Binary Automatic Computer BINAC

(1949).

Standards Eastern Automatic Computer SEAC

(1950).

Universal Automatic Computer UNIVAC I

(1951); one of the earliest commercially available computers designed for business applications.

Elliott Brothers Elliott 153

Early computer from the UK (1954).

Bendix G-15

(1956).

Librascope General Purpose Computer LGP-30

Used for various mathematical and engineering computations (1956).

Elliott Brothers Elliott 803

Small, medium-speed transistor digital computer manufactured by Elliott Brothers (1958).

Zeer Eenvoudige Binaire Reken Automaat (Very Simple Binary Automatic Calculator) ZEBRA

(1958).

D-17B guidance computer

(1962).

PDP-8/S

(1966).

General Electric GE-PAC 4040

Process control computer.

Datapoint 2200

Programmable terminal that could function as a simple personal computer (1971).

F14 CADC

transferred data serially but operated internally on many bits in parallel (1970).

HP-35

World's first handheld scientific calculator (1972).

CPU Scheduling

A process of determining which process will own the CPU for execution while another process is on hold.

Main goal of CPU Scheduling

To ensure that whenever the CPU remains idle, the OS selects one of the processes available in the ready queue for execution.

Preemptive Scheduling

Tasks are mostly assigned with priorities; a lower-priority task will stop to let a higher-priority task run first.

Non-Preemptive Scheduling

The CPU is allocated to a specific process until it finishes execution or switches context.

Burst Time / Execution Time / Running Time

Time required by the process to complete execution.

Arrival Time

When a process enters the ready state.

Finish Time

When a process completes and exits from the system.

Multiprogramming

Number of programs that can be present in memory at the same time.

Jobs

A program without user interaction.

User

A program with user interaction.

Process

Reference used for both jobs and users.

CPU/IO Burst Cycle

Characterizes process execution, alternating between CPU and I/O activity; CPU times are usually shorter than I/O times.

CPU Utilization

The main task of the OS is to make sure the CPU remains as busy as possible.

Throughput

The number of processes that finish execution per unit time; work completed per unit time.

Waiting Time

Amount of time a process needs to wait in the ready queue.

Response Time

Amount of time from when the request was submitted until the first response is produced.

Turnaround Time

Amount of time to execute a specific process; period between submission and completion.

First Come First Serve (FCFS)

Tasks are handled in the order they arrive.

Shortest-Job-First (SJF) Scheduling

Processes requiring the least amount of time to finish are executed first.

Shortest Remaining Time

Gives priority to the task that has the least amount of time left to complete.

Priority Scheduling

Tasks with higher priorities are executed first.

Round Robin Scheduling

Gives every task an equal share of the CPU time.

Multilevel Queue Scheduling

Processes are grouped into different queues based on characteristics like priority.

Multilevel Feedback Queue Scheduling

Uses a feedback mechanism to adjust the priority of a process based on its behavior over time.