I/O Device Management (IODM)

I/O device management is a very important part of the operating system, its form is very varied and made for special functions/operations. Some of them have been considered for the development of modern computers, such as starting from the mouse, keyboard, disk drive, display adapter, USB device, Network Device, Audio Device, Printer, Device for the disabled, and many more peripheral variants for special purposes.

Therefore, I/O device management is the broadest aspect of operating system design. In a computer system, I/O management is essential because I/O is a means for users to communicate with the computer. I/O management is also necessary so that users can directly use I/O devices without having to initialize them first. Therefore, in every operating system there is always an I/O manager.

I/O management has functions, including:

Send commands to I/O devices to provide services.
Handling I/O device interrupts
Handling errors on I/O devices
Provides an interface to the user.

The I/O subsystem must consider these 2 main factors:

Gravity Interface is standard for various devices, making it easy to add new devices.
Development for support for new device types and their existence is not standard.

A device driver is a module that can be installed in the Operating System to handle a specific device or category of similar devices.

There are two goals for designing I/O devices, namely:

Efficiency
Generality (Device-independence)

1. Efficiency

This is the most important aspect in I/O operations, because if this is not met, it will cause a bottleneck in the computer/computing system.

What is a Bottleneck?

Bottleneck, if loosely interpreted, means the neck of a bottle, but in the world of engineering, the term has its own meaning, namely the narrowing of the path, this is analogous to the "neck of a bottle", so you can imagine how the neck of a bottle is always narrower than its body.

Bottleneck In Computer Hardware

Nobody wants a bottleneck to occur. However, this condition can occur on all computers in the world. Bottlenecks are not like viruses. They are not related to the system, although in the end they will also have an impact on the system.

A computer that experiences a bottleneck will have its performance down. How could it not, the component specifications that are not comparable to other peripherals will certainly hinder an operation. Hardware with higher specifications must give way to 'slow' hardware, because it must wait for the process assigned to the 'bottleneck' to finish, automatically impacting system performance (performance gap). Consider the following example:

Processor: core 2 duo
RAM: ddr 5300 2 giga
VGA : 1600xt

From the example above, it can be concluded that a computer with these specifications can experience a "bottleneck", because the VGA specifications are classified as Low class, this is not comparable to the Processor and RAM specifications that are already classified above it (Middle End). Its poor performance will be known when involved in Graphic processing.

IO Response Time Performance Impact

Basically, every computer has a "bottleneck", it's just where it is located, that's what is studied in Computer Science I/O Device Management.

IO Bottleneck

2. Generality (Device-independence)

In addition to being related to simplicity and being error-free, it is also expected to handle all the various movements of the equipment. This statement is taken from observations of the I/O device process and how the operating system manages the equipment and I/O operations.

The software is organized as a single layer. Some lower layers are responsible for buffering (bridging) communication to the hardware, while some upper layers are responsible for buffering (bridging) communication to the user, such as providing an attractive and user-friendly interface.

The opposite of device dependent, Device Independent is a computer hardware that can be integrated into a computer without using supporting software (driver) and can be run directly in the computer's operating system (plug & play). Example; Processor, RAM, Hard disk, and CD/DVD ROM.

Example of Input Output (I/O) Device

1. Input Device

It is a tool used to receive input from outside the system, and can be in the form of signal input or maintenance input.

In a computer system, input signals are data entered into the computer system, while maintenance input is a program used to process the entered data. Thus, input devices are used not only to enter data but also to enter programs.

Input device equipment can be classified into 2, namely direct and indirect input devices:

Direct input devices are input devices that are entered and processed directly by the processing device.
Indirect input devices go through certain media before an input is processed by a processing device.

Direct Input Device Example

Direct input devices can be keyboards, pointing devices (e.g. mouse, touch screen, light pen, digitizer graphics tablet), scanners (e.g. magnetic ink character recognition, optical data reader or optical character recognition reader), sensors (e.g. digitizing camera), voice recognizers (e.g. microphone).

Indirect Input Device Examples

Meanwhile, indirect input devices, for example, include keypunch which is done via punched card media, key-to-tape which records data onto tape-shaped media before being processed by the processing tool, and key-to-disk which records data onto magnetic disk media (for example, diskette or hard disk) before being processed further.

Keyboard

A board consisting of buttons for typing sentences and other special symbols on a computer. Keyboard in Indonesian means finger keyboard or keyboard.

Keyboard Connection

By cable -- Serial -- Serial Port
With cable -- USB -- USB Port
Wireless (Without Cable)

Computer Connector Types

Other Examples of Input Devices

Video camera: video capture
Web cam : web page
Microphone : mic level input
Audio : line level input
Scanner: flat photo images, line art, paper documents
OCR: Optical Character Recognition
MICR : Magnetic Ink Character Recognition (bank checks)
Bar code : reader point of sale, turnaround documents
Biometric Input: fingerprint scan, voice recognition, face recognition, retinal scan, signature recognition.

2. Output Device

The output produced by the processor can be classified into four forms:

Writing (letters, numbers, special symbols),
Image (in the form of graphics or pictures),
Voice,
Another machine-readable form.
The first three groups: can be used directly by humans, while number 4 is usually used as input for further computer processes.

In terms of function, output devices are divided into 3, namely:

Hard-copy device, which is a tool used to print text and images on hard media such as paper or film. It is permanent and more portable (can be removed from the output device and can be carried anywhere). Common tools used for this are printers, plotters, and microfilm devices.

Soft-copy devices, namely tools used to display text and images on soft media in the form of electronic signals, for example: video displays, flat panels, and speakers.

Drive device or driver, which is a tool used to record symbols in a form that can only be read by machines on media such as magnetic disks or magnetic tape. This tool has a dual function, as an output tool and also as an input tool that uses magnetic disk media is a disk drive, and that uses magnetic tape media is a tape drive.

Monitor

There are various models and types of monitors, including the following:

CRT = cathode ray tube, can have a flat screen
LCD = liquid crystal display, also called flat panel
Gas Plasma = flat, with quality near CRT, but expensive and limited life

| Standard                          | Suggested Resolution                         | Maximum Possible Colors                             |
|-----------------------------------|----------------------------------------------|-----------------------------------------------------|
| Monochrome Display Adapter (MDA)  | 720 x 350                                    | 1 for text                                          |
| Video Graphics Array (VGA)        | 640 x 480 320 x 200                          | 16 256                                              |
| Extended Graphics Array (XGA)     | 1024 x 768 640 x 480                         | 256 65,536                                          |
| Super Video Graphics Array (SVGA) | 800 x 600 1024 x 768 1280 x 1024 1600 x 1200 | 16.7 million 16.7 million 16.7 million 16.7 million |
| Beyond SVGA                       | 1920 x 1440 2048 x 1536                      | 16.7 million 16.7 million                           |

Projectors

Projectors are almost the same as monitors. Its function is to display images/visuals resulting from data processing. However, infocus requires another object as a medium for receiving the transmitted image signals. The receiving medium should have a flat surface and be white (bright). Usually used is a white wall, whiteboard, or white cloth/screen that is stretched. However, many lay people call it an LCD even though it is not like that.