Modes Of Transfer in Input/Output Organization
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This document discusses different modes of data transfer between I/O devices and memory in a computer system. It describes three main modes: programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O involves constant CPU monitoring during transfers. Interrupt-initiated I/O uses interrupts to notify the CPU when a transfer is ready. DMA allows I/O devices to access memory directly without CPU involvement for improved efficiency.
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Computer architecture input output organization
Computer Architecture Input Output Organization seminar
Mustansiriya University
Department of Education
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Instruction cycle
The instruction cycle describes the process a computer follows to execute each machine language instruction. It involves 4 phases: 1) Fetch - the instruction is fetched from memory and placed in the instruction register. 2) Decode - the instruction is analyzed and decoded. 3) Execute - the processor executes the instruction by performing the specified operation. 4) The program counter is then incremented to point to the next instruction, and the cycle repeats. Each phase involves transferring data between the program counter, instruction register, memory, and other components via a common bus under the control of a timing unit. The instruction specifies the operation to be performed, such as a memory reference, register operation, or I/O access.
Unit 5 I/O organization
The document describes how input/output (I/O) devices communicate with the processor and memory. I/O devices are connected to the processor and memory via a shared bus. Each device has a unique address and uses address, data, and control lines on the bus. Interrupts allow I/O devices to signal the processor when they need attention, reducing wasted processor time. Multiple interrupt lines allow different devices to interrupt independently and ensure the correct interrupt service routine is executed.
DMA operation
1. Direct Memory Access (DMA) allows input/output devices to directly access main memory, bypassing the CPU to speed up memory transfers. This is managed by a DMA controller.
2. During a DMA transfer, the DMA controller gains control of the address bus, data bus, and control bus from the microprocessor to transfer data directly between an I/O port and memory.
3. The DMA controller has several options for transferring data, including cycle stealing for single byte transfers, burst mode for block transfers using address sequencing, and hidden DMA which occurs transparently when the CPU is not using the bus.
Memory organization (Computer architecture)
Memory is organized in a hierarchy with different levels providing trade-offs between speed and cost.
- Cache memory sits between the CPU and main memory for fastest access.
- Main memory (RAM) is where active programs and data reside and is faster than auxiliary memory but more expensive.
- Auxiliary memory (disks, tapes) provides backup storage and is slower than main memory but larger and cheaper.
Virtual memory manages this hierarchy through address translation techniques like paging that map virtual addresses to physical locations, allowing programs to access more memory than physically available. When data is needed from auxiliary memory a page fault occurs and page replacement algorithms determine what data to remove from main memory.
Direct memory access (dma)
Direct memory access (DMA) allows certain hardware subsystems to access computer memory independently of the central processing unit (CPU). During DMA transfer, the CPU is idle while an I/O device reads from or writes directly to memory using a DMA controller. This improves data transfer speeds as the CPU does not need to manage each memory access and can perform other tasks. DMA is useful when CPU cannot keep up with data transfer speeds or needs to work while waiting for a slow I/O operation to complete.
Modes of transfer
Introduction
Different modes of data transfer
Programmed I/O
Interrupt initiated I/O
Direct memory access (DMA)
Instruction pipelining
The document discusses instruction pipelining in CPUs. It explains that instruction pipelining achieves greater CPU performance by overlapping the execution of multiple instructions. It describes the different stages in a basic two-stage pipeline as fetch and execute. It then discusses how further dividing the pipeline into more stages, such as six stages for fetch, decode, calculate, fetch operands, execute, and writeback, can provide even higher performance. However, it notes conditional branches can reduce efficiency since the next instruction is unknown until the branch is resolved. Various techniques to handle branches like branch prediction, prefetching the target, and delayed branches are described to improve pipeline performance.
Recommended
Computer architecture input output organization
Computer Architecture Input Output Organization seminar
Mustansiriya University
Department of Education
Computer Science
Instruction cycle
The instruction cycle describes the process a computer follows to execute each machine language instruction. It involves 4 phases: 1) Fetch - the instruction is fetched from memory and placed in the instruction register. 2) Decode - the instruction is analyzed and decoded. 3) Execute - the processor executes the instruction by performing the specified operation. 4) The program counter is then incremented to point to the next instruction, and the cycle repeats. Each phase involves transferring data between the program counter, instruction register, memory, and other components via a common bus under the control of a timing unit. The instruction specifies the operation to be performed, such as a memory reference, register operation, or I/O access.
Unit 5 I/O organization
The document describes how input/output (I/O) devices communicate with the processor and memory. I/O devices are connected to the processor and memory via a shared bus. Each device has a unique address and uses address, data, and control lines on the bus. Interrupts allow I/O devices to signal the processor when they need attention, reducing wasted processor time. Multiple interrupt lines allow different devices to interrupt independently and ensure the correct interrupt service routine is executed.
DMA operation
1. Direct Memory Access (DMA) allows input/output devices to directly access main memory, bypassing the CPU to speed up memory transfers. This is managed by a DMA controller.
2. During a DMA transfer, the DMA controller gains control of the address bus, data bus, and control bus from the microprocessor to transfer data directly between an I/O port and memory.
3. The DMA controller has several options for transferring data, including cycle stealing for single byte transfers, burst mode for block transfers using address sequencing, and hidden DMA which occurs transparently when the CPU is not using the bus.
Memory organization (Computer architecture)
Memory is organized in a hierarchy with different levels providing trade-offs between speed and cost.
- Cache memory sits between the CPU and main memory for fastest access.
- Main memory (RAM) is where active programs and data reside and is faster than auxiliary memory but more expensive.
- Auxiliary memory (disks, tapes) provides backup storage and is slower than main memory but larger and cheaper.
Virtual memory manages this hierarchy through address translation techniques like paging that map virtual addresses to physical locations, allowing programs to access more memory than physically available. When data is needed from auxiliary memory a page fault occurs and page replacement algorithms determine what data to remove from main memory.
Direct memory access (dma)
Direct memory access (DMA) allows certain hardware subsystems to access computer memory independently of the central processing unit (CPU). During DMA transfer, the CPU is idle while an I/O device reads from or writes directly to memory using a DMA controller. This improves data transfer speeds as the CPU does not need to manage each memory access and can perform other tasks. DMA is useful when CPU cannot keep up with data transfer speeds or needs to work while waiting for a slow I/O operation to complete.
Modes of transfer
Introduction
Different modes of data transfer
Programmed I/O
Interrupt initiated I/O
Direct memory access (DMA)
Instruction pipelining
The document discusses instruction pipelining in CPUs. It explains that instruction pipelining achieves greater CPU performance by overlapping the execution of multiple instructions. It describes the different stages in a basic two-stage pipeline as fetch and execute. It then discusses how further dividing the pipeline into more stages, such as six stages for fetch, decode, calculate, fetch operands, execute, and writeback, can provide even higher performance. However, it notes conditional branches can reduce efficiency since the next instruction is unknown until the branch is resolved. Various techniques to handle branches like branch prediction, prefetching the target, and delayed branches are described to improve pipeline performance.
Modes of data transfer.computer architecture.
This document presents a summary of three modes of data transfer - programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O uses CPU instructions to monitor data transfer between CPU registers and peripherals. Interrupt-initiated I/O uses interrupts to inform the CPU when devices are ready to transfer data. DMA allows devices to access memory directly using bus request/grant signals, leaving the CPU free to perform other tasks. The document compares the three modes and references additional online sources for information.
Memory organization in computer architecture
Memory organization in computer architecture
Volatile Memory
Non-Volatile Memory
Memory Hierarchy
Memory Access Methods
Random Access
Sequential Access
Direct Access
Main Memory
DRAM
SRAM
NVRAM
RAM: Random Access Memory
ROM: Read Only Memory
Auxiliary Memory
Cache Memory
Hit Ratio
Associative Memory
Instruction pipeline: Computer Architecture
Pipelining is an speed up technique where multiple instructions are overlapped in execution on a processor. It is an important topic in Computer Architecture.
This slide try to relate the problem with real life scenario for easily understanding the concept and show the major inner mechanism.
Asynchronous Data Transfer.pptx
1) Asynchronous data transfer uses control signals rather than a shared clock to communicate between devices. There are two methods: strobe signals with one control line, and handshaking with two control lines.
2) In strobe signaling, either the source or destination can initiate data transfer by activating a strobe pulse along with data on the data bus. There is no confirmation that the data was received.
3) Handshaking uses two control lines - one for data validity from source to destination, and another for data acceptance from destination to source. This allows each device to operate independently while confirming the data transfer was completed.
Memory organisation
Memory is an essential component of computers that is used to store programs and data. Computers typically have three levels of memory: main memory, secondary memory, and cache memory. Main memory is fast memory that stores programs and data being executed. Secondary memory is permanent storage for programs and data used less frequently. Cache memory sits between the CPU and main memory for faster access. Memory is also classified by location, access method, volatility, and type.
Input Output Organization
The document discusses various methods for input/output (IO) in computer systems, including IO interfaces, programmed IO, interrupt-initiated IO, direct memory access (DMA), and input-output processors (IOPs). It describes how each method facilitates the transfer of data between the CPU, memory, and external IO devices.
IO Techniques in Computer Organization
The document discusses three different I/O techniques:
1. Programmed I/O - The CPU controls the entire I/O process and must periodically check device status, wasting CPU time.
2. Interrupt-driven I/O - The CPU issues a command and is freed up while the device operates. The device then interrupts the CPU when ready.
3. Direct memory access (DMA) - Allows devices to communicate directly with memory without involving the CPU, using a DMA controller. This overcomes CPU waiting and avoids repeated status checks.
i/o interface
The document discusses application I/O interfaces and their characteristics. Application I/O interfaces provide standard ways for operating systems to treat I/O devices uniformly by hiding differences through device drivers. I/O interfaces have characteristics like their data transfer mode (character or block), access method (sequential or random), transfer schedule (synchronous or asynchronous), ability to be shared, speed, and supported input/output directions.
Direct access memory
DMA stands for Direct memory access and is a method of transferring data from the computers RAM to another part of the computer without processing it using the CPU.
Multiprocessor
This document discusses multiprocessor systems, including their interconnection structures, interprocessor arbitration, communication and synchronization, and cache coherence. Multiprocessor systems connect two or more CPUs with shared memory and I/O to improve reliability and enable parallel processing. They use various interconnection structures like buses, switches, and hypercubes. Arbitration logic manages shared resources and bus access. Synchronization ensures orderly access to shared data through techniques like semaphores. Cache coherence protocols ensure data consistency across processor caches and main memory.
Computer instructions
An instruction format consists of bits that specify an operation to perform on data in computer memory. The processor fetches instructions from memory and decodes the bits to execute them. Instruction formats have operation codes to define operations like addition and an address field to specify where data is located. Computers may have different instruction sets.
Register transfer and micro-operation
1) The document discusses different types of micro-operations including arithmetic, logic, shift, and register transfer micro-operations.
2) It provides examples of common arithmetic operations like addition, subtraction, increment, and decrement. It also describes logic operations like AND, OR, XOR, and complement.
3) Shift micro-operations include logical shifts, circular shifts, and arithmetic shifts which affect the serial input differently.
Ram and-rom-chips
RAM is the main memory that allows bidirectional transfer of data via its data bus. It has a capacity of 128 bytes addressed by a 7-bit address. ROM can only read and can store more data than RAM in the same size chip. A memory address map assigns addresses to RAM and ROM chips. RAM uses address lines 1-7 and is selected by address lines 8-9 through a decoder. ROM uses address lines 1-9 and is selected by address line 10.
Direct memory access
This document discusses different types of data transfer modes between I/O devices and memory, including programmed I/O, interrupt-driven I/O, and direct memory access (DMA). It explains that DMA allows I/O devices to access memory directly without CPU intervention by using a DMA controller. The basic operations of DMA include the DMA controller gaining control of the system bus, transferring data directly between memory and I/O devices by updating address and count registers, and then relinquishing control back to the CPU. Different DMA transfer techniques like byte stealing, burst, and continuous modes are also covered.
Cache memory
Cache memory is a small, fast memory located between the CPU and main memory. It stores copies of frequently used instructions and data to accelerate access and improve performance. There are different mapping techniques for cache including direct mapping, associative mapping, and set associative mapping. When the cache is full, replacement algorithms like LRU and FIFO are used to determine which content to remove. The cache can write to main memory using either a write-through or write-back policy.
Dma
Direct Memory Access (DMA) allows for the direct transfer of data between memory and I/O devices without intervention from the CPU. A DMA controller handles the transfer, freeing up the CPU to perform other tasks. The DMA controller connects the I/O device, memory, and system buses, initiating transfers when instructed by the CPU and notifying the CPU upon completion through interrupts. This improves system performance by bypassing the CPU for large data transfers between memory and I/O.
design of accumlator
The document discusses the accumulator register in a CPU. It describes the accumulator as a short-term storage register for arithmetic and logic operations. It contains details about the inputs and outputs to the accumulator from other registers like the data register and input register. It also explains the different microoperations that can be performed on the accumulator like addition, transfer, complement, and shift operations. The control gates for these microoperations are also defined.
Cache memory
About Cache Memory
working of cache memory
levels of cache memory
mapping techniques for cache memory
1. direct mapping techniques
2. Fully associative mapping techniques
3. set associative mapping techniques
Cache memroy organization
cache coherency
every thing in detail
Modes of transfer - Computer Organization & Architecture - Nithiyapriya Pasav...
The document discusses three modes of data transfer between the central processing unit (CPU) and input/output (I/O) devices: programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O requires the CPU to continuously monitor the I/O device for data readiness, slowing performance. Interrupt-initiated I/O allows the I/O device to generate interrupts when ready, pausing the CPU to service transfers. DMA bypasses the CPU by allowing direct memory access between I/O devices and memory, speeding large data transfers.
Input output organization
The document discusses various aspects of I/O organization in a computer system. It describes the input-output interface that provides a method for transferring information between internal storage and external I/O devices. It discusses asynchronous data transfer techniques like strobe control and handshaking. It also covers asynchronous serial transmission, different modes of data transfer like programmed I/O, interrupt-initiated I/O, and direct memory access (DMA).
discuss the drawbacks of programmed and interrupt driven io and des.pdf
discuss the drawbacks of programmed and interrupt driven i/o and describe in general the
functionality of the DNA
Solution
Programmed I/O
Programmed I/O (PIO) refers to data transfers initiated by a CPU under driver software control
to access registers or memory on a device.
The CPU issues a command then waits for I/O operations to be complete. As the CPU is faster
than the I/O module, the problem with programmed I/O is that the CPU has to wait a long time
for the I/O module of concern to be ready for either reception or transmission of data. The CPU,
while waiting, must repeatedly check the status of the I/O module, and this process is known as
Polling. As a result, the level of the performance of the entire system is severely degraded.
Programmed I/O basically works in these ways:
Interrupt
The CPU issues commands to the I/O module then proceeds with its normal work until
interrupted by I/O device on completion of its work.
For input, the device interrupts the CPU when new data has arrived and is ready to be retrieved
by the system processor. The actual actions to perform depend on whether the device uses I/O
ports, memory mapping.
For output, the device delivers an interrupt either when it is ready to accept new data or to
acknowledge a successful data transfer. Memory-mapped and DMA-capable devices usually
generate interrupts to tell the system they are done with the buffer.
Although Interrupt relieves the CPU of having to wait for the devices, but it is still inefficient in
data transfer of large amount because the CPU has to transfer the data word by word between I/O
module and memory.
The main limitation of programmed I/O and interrupt driven I/O is given below:
Programmed I/O
Each instructions selects one I/O device (by number) and transfers a single character (byte)
Example: microprocessor controlled video terminal.
Four registers: input status and character, output status and character.
Interrupt-driven I/O
Primary disadvantage of programmed I/O is that CPU spends most of its time in a tight loop
waiting for the device to become ready. This is called busy waiting.
With interrupt-driven I/O, the CPU starts the device and tells it to generate an interrupt when it is
finished.
Done by setting interrupt-enable bit in status register.
Still requires an interrupt for every character read or written.
Interrupting a running process is an expensive business (requires saving context).
Requires extra hardware (DMA controller chip).
All these limitation can be overcome by the Introduction of DMA (Direct Memory Access)
To write block of 32 bytes from memory address 100 to device 4
1. CPU writes 32, 100, 4 into the first three DMA registers (memory address, count, device
number)
2. CPU puts code for WRITE (say 1) into fourth (direction) DMA register, which signals DMA
controller to begin operation
3. Controller reads (via bus request as CPU would) byte 100 from memory
4. Controller makes I/O request to write to device 4
5. Controller increments m.
Modes of data transfer
This document discusses different modes of data transfer between a central computer and input/output devices. It describes three main modes: programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O involves constant CPU monitoring of data transfers. Interrupt-initiated I/O uses interrupts to signal the CPU when a transfer is ready. DMA allows direct transfer between peripherals and memory without using the CPU. The document provides details on how each mode functions and when they may be used.
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What's hot
Modes of data transfer.computer architecture.
This document presents a summary of three modes of data transfer - programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O uses CPU instructions to monitor data transfer between CPU registers and peripherals. Interrupt-initiated I/O uses interrupts to inform the CPU when devices are ready to transfer data. DMA allows devices to access memory directly using bus request/grant signals, leaving the CPU free to perform other tasks. The document compares the three modes and references additional online sources for information.
Memory organization in computer architecture
Memory organization in computer architecture
Volatile Memory
Non-Volatile Memory
Memory Hierarchy
Memory Access Methods
Random Access
Sequential Access
Direct Access
Main Memory
DRAM
SRAM
NVRAM
RAM: Random Access Memory
ROM: Read Only Memory
Auxiliary Memory
Cache Memory
Hit Ratio
Associative Memory
Instruction pipeline: Computer Architecture
Pipelining is an speed up technique where multiple instructions are overlapped in execution on a processor. It is an important topic in Computer Architecture.
This slide try to relate the problem with real life scenario for easily understanding the concept and show the major inner mechanism.
Asynchronous Data Transfer.pptx
1) Asynchronous data transfer uses control signals rather than a shared clock to communicate between devices. There are two methods: strobe signals with one control line, and handshaking with two control lines.
2) In strobe signaling, either the source or destination can initiate data transfer by activating a strobe pulse along with data on the data bus. There is no confirmation that the data was received.
3) Handshaking uses two control lines - one for data validity from source to destination, and another for data acceptance from destination to source. This allows each device to operate independently while confirming the data transfer was completed.
Memory organisation
Memory is an essential component of computers that is used to store programs and data. Computers typically have three levels of memory: main memory, secondary memory, and cache memory. Main memory is fast memory that stores programs and data being executed. Secondary memory is permanent storage for programs and data used less frequently. Cache memory sits between the CPU and main memory for faster access. Memory is also classified by location, access method, volatility, and type.
Input Output Organization
The document discusses various methods for input/output (IO) in computer systems, including IO interfaces, programmed IO, interrupt-initiated IO, direct memory access (DMA), and input-output processors (IOPs). It describes how each method facilitates the transfer of data between the CPU, memory, and external IO devices.
IO Techniques in Computer Organization
The document discusses three different I/O techniques:
1. Programmed I/O - The CPU controls the entire I/O process and must periodically check device status, wasting CPU time.
2. Interrupt-driven I/O - The CPU issues a command and is freed up while the device operates. The device then interrupts the CPU when ready.
3. Direct memory access (DMA) - Allows devices to communicate directly with memory without involving the CPU, using a DMA controller. This overcomes CPU waiting and avoids repeated status checks.
i/o interface
The document discusses application I/O interfaces and their characteristics. Application I/O interfaces provide standard ways for operating systems to treat I/O devices uniformly by hiding differences through device drivers. I/O interfaces have characteristics like their data transfer mode (character or block), access method (sequential or random), transfer schedule (synchronous or asynchronous), ability to be shared, speed, and supported input/output directions.
Direct access memory
DMA stands for Direct memory access and is a method of transferring data from the computers RAM to another part of the computer without processing it using the CPU.
Multiprocessor
This document discusses multiprocessor systems, including their interconnection structures, interprocessor arbitration, communication and synchronization, and cache coherence. Multiprocessor systems connect two or more CPUs with shared memory and I/O to improve reliability and enable parallel processing. They use various interconnection structures like buses, switches, and hypercubes. Arbitration logic manages shared resources and bus access. Synchronization ensures orderly access to shared data through techniques like semaphores. Cache coherence protocols ensure data consistency across processor caches and main memory.
Computer instructions
An instruction format consists of bits that specify an operation to perform on data in computer memory. The processor fetches instructions from memory and decodes the bits to execute them. Instruction formats have operation codes to define operations like addition and an address field to specify where data is located. Computers may have different instruction sets.
Register transfer and micro-operation
1) The document discusses different types of micro-operations including arithmetic, logic, shift, and register transfer micro-operations.
2) It provides examples of common arithmetic operations like addition, subtraction, increment, and decrement. It also describes logic operations like AND, OR, XOR, and complement.
3) Shift micro-operations include logical shifts, circular shifts, and arithmetic shifts which affect the serial input differently.
Ram and-rom-chips
RAM is the main memory that allows bidirectional transfer of data via its data bus. It has a capacity of 128 bytes addressed by a 7-bit address. ROM can only read and can store more data than RAM in the same size chip. A memory address map assigns addresses to RAM and ROM chips. RAM uses address lines 1-7 and is selected by address lines 8-9 through a decoder. ROM uses address lines 1-9 and is selected by address line 10.
Direct memory access
This document discusses different types of data transfer modes between I/O devices and memory, including programmed I/O, interrupt-driven I/O, and direct memory access (DMA). It explains that DMA allows I/O devices to access memory directly without CPU intervention by using a DMA controller. The basic operations of DMA include the DMA controller gaining control of the system bus, transferring data directly between memory and I/O devices by updating address and count registers, and then relinquishing control back to the CPU. Different DMA transfer techniques like byte stealing, burst, and continuous modes are also covered.
Cache memory
Cache memory is a small, fast memory located between the CPU and main memory. It stores copies of frequently used instructions and data to accelerate access and improve performance. There are different mapping techniques for cache including direct mapping, associative mapping, and set associative mapping. When the cache is full, replacement algorithms like LRU and FIFO are used to determine which content to remove. The cache can write to main memory using either a write-through or write-back policy.
Dma
Direct Memory Access (DMA) allows for the direct transfer of data between memory and I/O devices without intervention from the CPU. A DMA controller handles the transfer, freeing up the CPU to perform other tasks. The DMA controller connects the I/O device, memory, and system buses, initiating transfers when instructed by the CPU and notifying the CPU upon completion through interrupts. This improves system performance by bypassing the CPU for large data transfers between memory and I/O.
design of accumlator
The document discusses the accumulator register in a CPU. It describes the accumulator as a short-term storage register for arithmetic and logic operations. It contains details about the inputs and outputs to the accumulator from other registers like the data register and input register. It also explains the different microoperations that can be performed on the accumulator like addition, transfer, complement, and shift operations. The control gates for these microoperations are also defined.
Cache memory
About Cache Memory
working of cache memory
levels of cache memory
mapping techniques for cache memory
1. direct mapping techniques
2. Fully associative mapping techniques
3. set associative mapping techniques
Cache memroy organization
cache coherency
every thing in detail
Modes of transfer - Computer Organization & Architecture - Nithiyapriya Pasav...
The document discusses three modes of data transfer between the central processing unit (CPU) and input/output (I/O) devices: programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O requires the CPU to continuously monitor the I/O device for data readiness, slowing performance. Interrupt-initiated I/O allows the I/O device to generate interrupts when ready, pausing the CPU to service transfers. DMA bypasses the CPU by allowing direct memory access between I/O devices and memory, speeding large data transfers.
Input output organization
The document discusses various aspects of I/O organization in a computer system. It describes the input-output interface that provides a method for transferring information between internal storage and external I/O devices. It discusses asynchronous data transfer techniques like strobe control and handshaking. It also covers asynchronous serial transmission, different modes of data transfer like programmed I/O, interrupt-initiated I/O, and direct memory access (DMA).
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Modes of transfer - Computer Organization & Architecture - Nithiyapriya Pasav...
Modes of transfer - Computer Organization & Architecture - Nithiyapriya Pasav...
Similar to Modes Of Transfer in Input/Output Organization
discuss the drawbacks of programmed and interrupt driven io and des.pdf
discuss the drawbacks of programmed and interrupt driven i/o and describe in general the
functionality of the DNA
Solution
Programmed I/O
Programmed I/O (PIO) refers to data transfers initiated by a CPU under driver software control
to access registers or memory on a device.
The CPU issues a command then waits for I/O operations to be complete. As the CPU is faster
than the I/O module, the problem with programmed I/O is that the CPU has to wait a long time
for the I/O module of concern to be ready for either reception or transmission of data. The CPU,
while waiting, must repeatedly check the status of the I/O module, and this process is known as
Polling. As a result, the level of the performance of the entire system is severely degraded.
Programmed I/O basically works in these ways:
Interrupt
The CPU issues commands to the I/O module then proceeds with its normal work until
interrupted by I/O device on completion of its work.
For input, the device interrupts the CPU when new data has arrived and is ready to be retrieved
by the system processor. The actual actions to perform depend on whether the device uses I/O
ports, memory mapping.
For output, the device delivers an interrupt either when it is ready to accept new data or to
acknowledge a successful data transfer. Memory-mapped and DMA-capable devices usually
generate interrupts to tell the system they are done with the buffer.
Although Interrupt relieves the CPU of having to wait for the devices, but it is still inefficient in
data transfer of large amount because the CPU has to transfer the data word by word between I/O
module and memory.
The main limitation of programmed I/O and interrupt driven I/O is given below:
Programmed I/O
Each instructions selects one I/O device (by number) and transfers a single character (byte)
Example: microprocessor controlled video terminal.
Four registers: input status and character, output status and character.
Interrupt-driven I/O
Primary disadvantage of programmed I/O is that CPU spends most of its time in a tight loop
waiting for the device to become ready. This is called busy waiting.
With interrupt-driven I/O, the CPU starts the device and tells it to generate an interrupt when it is
finished.
Done by setting interrupt-enable bit in status register.
Still requires an interrupt for every character read or written.
Interrupting a running process is an expensive business (requires saving context).
Requires extra hardware (DMA controller chip).
All these limitation can be overcome by the Introduction of DMA (Direct Memory Access)
To write block of 32 bytes from memory address 100 to device 4
1. CPU writes 32, 100, 4 into the first three DMA registers (memory address, count, device
number)
2. CPU puts code for WRITE (say 1) into fourth (direction) DMA register, which signals DMA
controller to begin operation
3. Controller reads (via bus request as CPU would) byte 100 from memory
4. Controller makes I/O request to write to device 4
5. Controller increments m.
Modes of data transfer
This document discusses different modes of data transfer between a central computer and input/output devices. It describes three main modes: programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). Programmed I/O involves constant CPU monitoring of data transfers. Interrupt-initiated I/O uses interrupts to signal the CPU when a transfer is ready. DMA allows direct transfer between peripherals and memory without using the CPU. The document provides details on how each mode functions and when they may be used.
MODES OF TRANSFER.pptx
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ch -6 IO.pptx
The document discusses different modes of data transfer between the central processing unit (CPU) and input/output (I/O) devices, including programmed I/O, interrupt-initiated I/O, and direct memory access (DMA). It describes how each mode functions, such as the CPU monitoring flags in programmed I/O or an I/O device interrupting the CPU when ready in interrupt-initiated I/O. The document also covers priority interrupts, DMA controllers that allow direct transfers between memory and I/O devices, and input/output processors that offload I/O tasks from the CPU.
Chapter 4
The document discusses input/output (I/O) problems in computer systems and solutions to those problems. Some key issues addressed are the variety of peripheral devices with different data rates and formats, and the mismatch between peripheral and processor speeds. The document describes I/O modules that interface between the CPU/memory and peripherals. I/O modules handle control, buffering, error detection and allow different I/O techniques like programmed I/O, interrupt-driven I/O and direct memory access (DMA) to transfer data efficiently.
Data transfer techniques 8085
The document discusses various data transfer techniques used in microprocessors, including synchronous, asynchronous, interrupt-driven I/O, DMA, and programmed I/O. It explains that synchronous transfer uses compatible speeds, asynchronous uses handshaking, interrupt-driven reduces processor waiting, DMA allows direct memory access to bypass the CPU, and programmed I/O uses the CPU to directly control I/O operations. It also covers serial vs parallel transmission and differences between them.
Lecture 9.pptx
This document discusses different techniques for data transfer between the CPU and I/O devices, including programmed I/O, interrupt-driven I/O, and direct memory access (DMA). It describes the basic functioning of an I/O module, comparing programmed I/O to interrupt-driven I/O. It then provides details on DMA, including how it allows high-speed transfer of data directly between memory and I/O devices without CPU involvement. The document also covers I/O interfaces, asynchronous data transfer methods like handshaking, and serial transmission techniques.
Chapter 5 IO Unit.pptx we are electrical
The document discusses input/output (I/O) modules in a computer system. I/O modules interface between peripheral devices and the system bus. They contain logic to communicate with different types of peripherals using various techniques, including programmed I/O, interrupt-driven I/O, and direct memory access (DMA). DMA allows large blocks of data to be transferred directly between memory and peripherals without using the processor's bandwidth, improving transfer speeds.
Unit3 input
There are three main modes of data transfer between CPU and I/O devices:
1) Programmed I/O where the CPU actively manages all data transfers by executing I/O instructions.
2) Interrupt-driven I/O where devices interrupt the CPU when data is available to transfer, allowing the CPU to perform other tasks in the meantime.
3) Direct Memory Access (DMA) where an I/O controller directly accesses memory to transfer data without CPU involvement, freeing up the CPU.
Transfer Modes | Computer Science
Modes of transfer refer to the various modes by which the data residing in the memory is transferred to CPU or back to memory. Let us first discuss the need to transfer data. The data originates from the input units. Copy the link given below and paste it in new browser window to get more information on Transfer Modes:- http://www.transtutors.com/homework-help/computer-science/transfer-modes.aspx
I/o management and disk scheduling .pptx
This document provides an overview of I/O management and disk scheduling in operating systems. It begins with an introduction to different categories of I/O devices and how they vary. It then covers techniques for performing I/O like programmed I/O, interrupt-driven I/O, and direct memory access. The document discusses the evolution of the I/O function and a hierarchical model for organizing I/O. It also outlines concepts like I/O buffering, disk scheduling parameters, RAID levels, and disk caching.
COMPUTER ORGANIZATION NOTES Unit 3 4
This document discusses input/output (I/O) organization in computers. It covers several topics:
- I/O devices can connect to the CPU via a single shared bus using memory-mapped I/O. This allows direct reading/writing of device registers via memory addresses.
- Interrupts allow I/O devices to signal the CPU when an event occurs, so it can pause its current task and service the device. Interrupt handling involves disabling interrupts, servicing the device, then re-enabling interrupts.
- Direct memory access (DMA) allows high-speed transfer of large blocks of data directly between I/O devices and memory without CPU involvement, improving performance over interrupt-driven
Data transfer system
This document discusses different techniques for transferring data between a microprocessor and input/output (I/O) devices. It describes synchronous and asynchronous data transfer formats. It also discusses parallel and serial modes of data transfer. The document outlines different schemes for microprocessor-controlled data transfer, including programmed and interrupt-driven transfers. It notes the limitations of these approaches. Finally, it introduces device-controlled data transfer using direct memory access (DMA), which improves transfer speeds by bypassing the microprocessor. DMA transfer operation and different DMA transfer types are also summarized.
IO_ORGANIZATION.pdf
The document discusses input/output (I/O) organization in computers. It describes how the I/O subsystem provides communication between external devices and the central processing system. Common peripheral devices include monitors, keyboards, printers, and magnetic tapes. The document outlines different I/O techniques including programmed I/O, interrupt-driven I/O, and direct memory access. It also discusses I/O interfaces, addressing schemes, and how interrupts work to signal device completion.
Input-Output Modules
The document discusses input-output (I/O) modules in computers. It explains that I/O modules play a crucial role in allowing communication between a computer's central processing unit (CPU) and external devices. I/O modules connect devices to the computer's system bus and control the exchange of data between devices and main memory or the CPU. They help address issues like differing data formats and speeds between devices and the CPU. The document outlines various I/O techniques like programmed I/O, interrupt-driven I/O, and direct memory access (DMA) that use I/O modules to facilitate input and output.
I/O Management
The document provides information about input/output management in operating systems. It discusses I/O devices, device controllers, direct memory access and DMA controllers. Some key points include:
I/O devices are divided into block devices which access fixed size blocks of data and character devices which access data as a sequential stream. Device controllers act as an interface between devices and device drivers. Direct memory access allows data transfer between memory and devices without CPU involvement by using a DMA controller. DMA controllers program data transfers and arbitrate bus access.
DMA Controller Presentation
This document provides information about direct memory access (DMA) and input/output (I/O) techniques used by operating systems. It lists six group members and their topics which include DMA, how it works, and comparisons of polling and interrupts. DMA allows hardware devices to access memory independently of the CPU. The operating system uses DMA hardware by instructing a device driver to transfer data to a buffer, then the disk controller performs the DMA transfer to that address. Polling checks device status periodically while interrupts use hardware signals to notify the CPU when a device needs attention.
Data transferschemes
This document discusses different techniques for transferring data between input/output (I/O) devices and the central processing unit (CPU). It describes programmed I/O, interrupt-driven I/O, and direct memory access (DMA). Programmed I/O involves the CPU continuously checking I/O device status, wasting CPU time. Interrupt-driven I/O improves efficiency by allowing devices to interrupt the CPU when ready. DMA is most efficient as it transfers data directly between memory and I/O devices without using the CPU, which then regains control after the transfer.
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discuss the drawbacks of programmed and interrupt driven io and des.pdf
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Modes Of Transfer in Input/Output Organization
- 1. BY: PULKIT ZAVERI – 161080107063 MOHIT AGARWAL – 161080107026 SEM : 4 BRANCH : COMPUTER
- 2. WHY ARE THEY USED ? CPU merely executes instruction and accepts data temporally from I/O devices. Ultimate source and destination is memory. Data transfer is handled in a variety of modes.
- 3. WHAT ARE THE DIFFERENT MODES? Data transfer can be handled in one of Three Modes: Programmed I/O Interrupt-Initiated I/O Direct Memory Access (DMA)
- 4. PROGRAMMED I/O Each data item transfer is initiated by an I/O instruction written in a computer program. Transferring data under program control requires constant monitoring of the peripheral by CPU. In this method, the CPU stays in a program loop until I/O unit is ready for data transfer. This time-consuming process keeps the processor needlessly busy.
- 5. An example of data transfer from an I/O device through an interface into a CPU in given below: I/O DeviceCPU Data valid Data accepted Data bus Interface I/O Read Data bus Data Register Status Register F Address bus I/O Write
- 6. INTERRUPT-INITIATED I/O Instead of continuous monitoring of CPU, interface will be informed to issue an interrupt request signal. Meanwhile, CPU proceeds to execute another program and the interface keeps monitoring the device. When device is ready for data transfer, it generates interrupt request. Here the CPU stops the task it is performing, processes the data transfer then resumes the original task.
- 8. TYPES OF INTERRUPTS There are various sources of interrupts, these could be both internal or external : • Program Interrupts : They are generated by some condition that occurs as a result of an instruction execution. • Timer Interrupts : They are generated within the processor, and allow the OS to perform certain operations on regular basis. • I/O Interrupts : They are generated for initiation or completion of I/O operation. • Hardware Failure Interrupts : They are generated by failure, such as power failure or memory parity error.
- 9. DIRECT MEMORY ACCESS (DMA) Direct Memory Access (DMA) means CPU grants I/O module authority to read from or write to memory without involvement. DMA module itself controls exchange of data between main memory and the I/O device. CPU is only involved at the beginning and end of the transfer and interrupted only after entire block has been transferred.
- 10. DMA controller (DMAC) manages the data transfers and arbitrates access to the system bus.
- 11. DMA DATA TRANSFER MODES Data can be transferred in several different ways under DMA control : DMA BlockTransfer : In this mode a block of data of arbitrary length can be transferred in a single burst. Cycle Stealing Mode : Here, the DMA controller is allowed to use the system bus to transfer one word at a time, after which it must return control of the bus to CPU. Transparent DMA : In this mode DMA is allowed to steal only those cycles when the CPU is not using system bus.