I/O Channels and its types Last Updated : 12 Jul, 2025 Comments Improve Suggest changes Like Article Like Report I/O or input-output channels handle all the input/output operations by themselves which means it does not depend on any other hardware components. It uses enough memory to handle all the input/output tasks. In this article, we will see I/O channels and their types.What is I/O Channels?I/O Channels is an extension of the DMA concept. It has ability to execute I/O instructions using special-purpose processor on I/O channel and complete control over I/O operations. Processor does not execute I/O instructions itself. Processor initiates I/O transfer by instructing the I/O channel to execute a program in memory. Advantages of I/O ChannelsI/O channels use their own processors for their I/O tasks and operation.It reduces the CPU workload for I/O operations because it directly connects to the main memory.It is responsible for handling errors that arises from I/O operations and tasks.Disadvantages of I/O ChannelsMultiple tasks run simultaneously which is complex when there is a large amount of data.Multiple I/O processors causes a Synchronization issues.Hardware components present in I/O channels are costly.Types of I/O Channels There are two types of I/O channels available: Selector ChannelSelector channel controls multiple high-speed devices. It is dedicated to the transfer of data with one of the devices. In selector channel, each device is handled by a controller or I/O module. It controls the I/O controllers shown in the figure. Selector ChannelAdvantages of Selector Channel Selector channel used high speed I/O devices that improve the system performance.Fast data transfer.Synchronization issues do not occur because in the selector one device and task run on that time.Disadvantages of Selector ChannelIt handles only one I/O task at a time.It does not handle multiple devices at a time that means only one task and device run on that time.It is complex.Multiplexer ChannelMultiplexer channel is a DMA controller that can handle multiple devices at the same time. It can do block transfers for several devices at once. There are basically two types of multiplexers used in this channelByte Multiplexer - It is used for low-speed devices. It transmits or accepts characters. Interleaves bytes from several devices. Block Multiplexer - It accepts or transmits block of characters. Interleaves blocks of bytes from several devices. Used for high-speed devices. Advantages of Multiplexer ChannelIt can handle multiple devices Simultaneously.It handles multiple tasks and I/O operations Simultaneously.It takes less time.Disadvantages of Multiplexer ChannelSlow I/O devices used in Multiplexer that impact the speed of data transmission.It is complex when we talk about handling multiple I/O operations.It occurs Synchronization issues.ConclusionI/O channels are not dependent on hardware components. They have their processors to handle input-output operations and tasks. When we talk about its cost, they have a low cost because they do everything independently and use our special processors to execute the instructions in the main memory. Comment More infoAdvertise with us P pp_pankaj Follow Improve Article Tags : Computer Organization & Architecture Similar Reads Computer Organization and Architecture Tutorial Computer architecture defines how a computer’s components communicate through electronic signals to perform input, processing, and output operations.It covers the design and organization of the CPU, memory, storage, and input/output devices.Describes how these components interact through buses, cont 4 min read Basic Computer InstructionsWhat is a Computer?A computer is an electronic device that processes data according to instructions provided by software programs. It takes input (data), processes it using a central processing unit (CPU), stores information, and produces output (results) to perform various tasks.Types of ComputersThere are various ty 8 min read Issues in Computer DesignComputer Design is the structure in which components relate to each other. 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To summarize, when I/O devices are ready for I/O transfer, they generate an interrupt request signal to the computer. The CPU receives this signal, suspends the current instructions it is exe 5 min read I/O Interface (Interrupt and DMA Mode)The method that is used to transfer information between internal storage and external I/O devices is known as I/O interface. The CPU is interfaced using special communication links by the peripherals connected to any computer system. These communication links are used to resolve the differences betw 6 min read Direct memory access with DMA controller 8257/8237Suppose any device which is connected to input-output port wants to transfer data to memory, first of all it will send input-output port address and control signal, input-output read to input-output port, then it will send memory address and memory write signal to memory where data has to be transfe 3 min read Computer Organization | Asynchronous input output synchronizationIntroduction : Asynchronous input/output (I/O) synchronization is a technique used in computer organization to manage the transfer of data between the central processing unit (CPU) and external devices. In asynchronous I/O synchronization, data transfer occurs at an unpredictable rate, with no fixed 7 min read Programmable peripheral interface 8255PPI 8255 is a general purpose programmable I/O device designed to interface the CPU with its outside world such as ADC, DAC, keyboard etc. We can program it according to the given condition. It can be used with almost any microprocessor. It consists of three 8-bit bidirectional I/O ports i.e. PORT A 4 min read Synchronous Data Transfer in Computer OrganizationIn Synchronous Data Transfer, the sending and receiving units are enabled with the same clock signal. It is possible between two units when each of them knows the behaviour of the other. The master performs a sequence of instructions for data transfer in a predefined order. All these actions are syn 4 min read Introduction of Input-Output ProcessorThe DMA mode of data transfer reduces the CPU's overhead when handling I/O operations. It also allows parallel processing between CPU and I/O operations. This parallelism is necessary to avoid the wastage of valuable CPU time when handling I/O devices whose speeds are much slower as compared to CPU. 5 min read MPU Communication in Computer OrganizationMPU communicates with the outside world with the help of some external devices which are known as Input/Output devices. The MPU accepts the binary data from input devices such as keyboard and analog/digital converters and sends data to output devices such as printers and LEDs. For performing this ta 4 min read Memory Mapped I/O and Isolated I/OCPU needs to communicate with the various memory and input-output devices (I/O). Data between the processor and these devices flow with the help of the system bus. There are three ways in which system bus can be allotted to them:Separate set of address, control and data bus to I/O and memory.Have co 5 min read Memory OrganizationIntroduction to memory and memory unitsMemory is required to save data and instructions. Memory is divided into cells, and they are stored in the storage space present in the computer. Every cell has its unique location/address. Memory is very essential for a computer as this is the way it becomes somewhat more similar to a human brain. 11 min read Memory Hierarchy Design and its CharacteristicsIn the Computer System Design, Memory Hierarchy is an enhancement to organize the memory such that it can minimize the access time. The Memory Hierarchy was developed based on a program behavior known as locality of references (same data or nearby data is likely to be accessed again and again). The 6 min read Register Allocations in Code GenerationRegisters are the fastest locations in the memory hierarchy. But unfortunately, this resource is limited. It comes under the most constrained resources of the target processor. Register allocation is an NP-complete problem. However, this problem can be reduced to graph coloring to achieve allocation 6 min read Cache MemoryCache memory is a small, fast storage space within a computer. It holds duplicates of data from commonly accessed locations in the main memory. The CPU contains several separate caches that store both instructions and data.Cache Memory The key function of cache memory is to reduce the average time n 5 min read Cache Organization | Set 1 (Introduction)Cache is close to CPU and faster than main memory. But at the same time is smaller than main memory. The cache organization is about mapping data in memory to a location in cache. A Simple Solution: One way to go about this mapping is to consider last few bits of long memory address to find small ca 3 min read Multilevel Cache OrganisationCache is a type of random access memory (RAM) used by the CPU to reduce the average time required to access data from memory. Multilevel caches are one of the techniques used to improve cache performance by reducing the miss penalty. The miss penalty refers to the additional time needed to retrieve 6 min read Difference between RAM and ROMMemory is an important part of the Computer which is responsible for storing data and information on a temporary or permanent basis. Memory can be classified into two broad categories: Primary Memory Secondary Memory What is Primary Memory? Primary Memory is a type of Computer Memory that the Prepro 7 min read Difference Between CPU Cache and TLBThe CPU Cache and Translation Lookaside Buffer (TLB) are two important microprocessor hardware components that improve system performance, although they have distinct functions. Even though some people may refer to TLB as a kind of cache, it's important to recognize the different functions they serv 4 min read Introduction to Solid-State Drive (SSD)A Solid-State Drive (SSD) is a non-volatile storage device that stores data without using any moving parts, unlike traditional Hard Disk Drives (HDDs), which have spinning disks and mechanical read/write heads. Because of this, SSDs are much faster, more durable, and quieter than HDDs. They load fil 7 min read Read and Write operations in MemoryA memory unit stores binary information in groups of bits called words. Data input lines provide the information to be stored into the memory, Data output lines carry the information out from the memory. The control lines Read and write specifies the direction of transfer of data. Basically, in the 3 min read PipeliningInstruction Level ParallelismInstruction Level Parallelism (ILP) is used to refer to the architecture in which multiple operations can be performed parallelly in a particular process, with its own set of resources - address space, registers, identifiers, state, and program counters. It refers to the compiler design techniques a 5 min read Computer Organization and Architecture | Pipelining | Set 1 (Execution, Stages and Throughput)Pipelining is a technique used in modern processors to improve performance by executing multiple instructions simultaneously. It breaks down the execution of instructions into several stages, where each stage completes a part of the instruction. These stages can overlap, allowing the processor to wo 9 min read Computer Organization and Architecture | Pipelining | Set 3 (Types and Stalling)Please see Set 1 for Execution, Stages and Performance (Throughput) and Set 2 for Dependencies and Data Hazard. Types of pipeline Uniform delay pipeline In this type of pipeline, all the stages will take same time to complete an operation. In uniform delay pipeline, Cycle Time (Tp) = Stage Delay If 3 min read Computer Organization and Architecture | Pipelining | Set 2 (Dependencies and Data Hazard)Please see Set 1 for Execution, Stages and Performance (Throughput) and Set 3 for Types of Pipeline and Stalling. Dependencies in a pipelined processor There are mainly three types of dependencies possible in a pipelined processor. These are : 1) Structural Dependency 2) Control Dependency 3) Data D 6 min read Last Minute Notes Computer Organization Table of ContentBasic TerminologyInstruction Set and Addressing ModesInstruction Design and FormatControl UnitMemory Organization I/O InterfacePipeliningIEEE Standard 754 Floating Point NumbersBasic TerminologyControl Unit - A control unit (CU) handles all processor control signals. It directs all i 15+ min read COA GATE PYQ's AND COA QuizGATE CS PreparationPreparing for the GATE exam can be straightforward if you know the right steps to take. This brief GATE CSE Preparation Guide will help you get started and stay on track as you prepare for one of the most important exams for admissions into IITs, NITs and other government colleges.Let's get started: 3 min read Like