Input/output

In computing, input/output or I/O (or informally, io or IO) is the communication between an information processing system (such as a computer) and the outside world, possibly a human or another information processing system.

see kast on arvuti

Arvuti eesmärk juhtida mingit protsessi/seadet sisendid on signaalid või andmed, mida vastu võetakse võetakse ja vastupidi
Seadmeid võivad kasutada inimesed või teised seadmed.
Modem-Modulate & demodulate. Liidab kaks signaali (Modulate) ja Lahutab kaks signaali(Demodulate)
Vanal ajal kasutati seda, et interneti saada..
I/O katergoorid- Human readable- printerid, video display, klavetuur, hiir (suitable for communicating with the computer user)
Machine readable- disk drives, USB keys, sensors(tajur), controllers(suitable for communicating with electronic equipment)
Communication- modems,digital line, drivers, network interface card (NIC(võrgukaart))(suitable for communicating with remote devices)
ERINEVUSED
- Data Rate (arvuti vastavuse kiirus)- there may be differences of magnitude between the data transfer rates
- Rakendus, kus ja mis eesmärgil kasutakse- the use to which a device is put has to incluence on the software
- complexity of control- the effect on the operating system ins filtered by the complexity of the I/O module that controls the device
- unit of transfer- data may be transferred as a stream of bytes or characters or in a larger blocks
- Data Representation- different data encoding schemes are used by different devices
- Error Conditions- the nature of errors, the way in which they are reported, their consequences, and available range of responses differs from one device to another
Arvutis on emaplaat, sellele paigutamine protsessori, sellel olemas kiibistikud- üks põhjasild, teine lõunasild. Põhjasild e. memory controller. Ühendab kiireid seadmed nt mälu, protsessor jne. Lõunasild ehk I/O controller- kettad, klaviatuurid, võrgukaardid-ICH

Arvuti arhidektuuris protsessori ja peamälu kombinatsioon on arvuti aju eest.
CPU+RAM=<3
In computer architecture, the combination of the CPU and main memory, to which the CPU can read or write directly using individual instructions, is considered the brain of a computer. Any transfer of information to or from the CPU/memory combo, for example by reading data from a disk drive, is considered I/O

Kuidas väljendseadmetaga suhelda?

Võime kasutda vahekontrollereid.
Kuidas andme mällu jõuvad?
Selleks, et mälus olevate asjadega midagi teha tuleb, need välja kutsude protsessorisse, sellega saab rääkida erinavatest seadme ajuriset või I/O kanalitest või ka isegi teatud algoritmidest(eeskiri) kuidas teha. Erinevate seadme keerukas ja kiirused peavad andmed jõudma mällu selleks, et neid oleks võimalik protsessori poolt töödelda arvutis ei juhtu midagi, kui see prossorisse ei jõua, kõik tuleb välja kutsuda protsessorisse nt isegi hiire liigutamine.
Selleks, et seadmed saaksid protsessoriga suhelda ma kasutame liidseid e interface (kõikide nuppude vajutamine)
sssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssnake
Handhsaking- et kõik saaksid tutvuda üksteisega (masinas)
interface kasutab selliseid käskusi- busy, ready, ja wait.
Organization of the I/O function

Three techniques for performing I/O are:
Programmed I/O
The processor issues an I/O command on behalf of a process to an I/O module; that process then busy waits for the operation to be completed before proceeding
Interrupt-driven I/O
The processor issues an I/O COMMAND on behalf of a process
if non-blocking- processor continues to execute instructions from

interrupt sources and processor handling In systems programming, an interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention. An interrupt alerts the processor to a high-priority condition requiring the interruption of the current code the processor is executing.
Interrupt is the shizzle

Direct Memory access

Design Objectives
Efficiency
Major effort in I/O design
Important because I/O operations often form a bottleneck
Most I/O devices are extremely slow compared with main memory and the processor
multiprogramming
The are that has received the most attention is disk I/O
Generality
Desirable to handle all devices in a uniform manner
Applies to both the way processes view I/O devices and the way the operating system manages I/O devices and operations

Buffering- puhverdamine
In computer science, a data buffer (or just buffer) is a region of a physical memory storage used to temporarily store data while it is being moved from one place to another.
Block-oriented device
Stores information in blocks that are usually of fixed size
transfers are made one block at a time
possible to reference data by its block number
disks and USB keys are examples
Stream-oriented device
transfers data in and out as a stream of bytes
no block structure
terminals, printers, communications ports, and most other devices that are not secondary storage are examples