Tuesday, November 29, 2005
DMA, IOP
What is handshaking?
When data is being transferred between two units, the units receiving the data responds with another control signal to acknowledge the receipt of the data. This type of agreement between two independent units is called handshaking.
What is synchronous transmission?
Synchronous transmission allows two units to share a common clock frequency and bits are transmitted continuously at the rate dictated by the clock pulse.
What is asynchronous transmission?
The asynchronous transmission allow data transfer between more than two systems, in which they use special bits. The characters send consists of three parts: a start bit, the character bits, and the stop bits. It starts transmission for start bit, and stops on receiving stop bit.
Define baud rate.
Baud rate is defined as the rate at which serial information is transmitted and is equivalent to the data transfer in bits per second.
What are the different modes of data transfer?
Data transfer to and from peripherals could be carried out in one of the following modes: i) Programmed I/O ii) Interrupt initiated I/O iii)Direct memory access
What is programmed I/O mode of data transfer?
Programmed I/O operations are carried out by the result of I/O instructions written to the computer program. Each data item transfer is initiated by an instruction in the program.
What is interrupt?
When an interrupt request signal is issued, the processor suspends the execution of the currently executing program, and starts the execution of the interrupted program. Then, it starts the suspended program. This process is called interrupt.
What is DMA?
Direct memory access allows transfer of data into and out of the memory units through the memory bus, with out the use of CPU. This is called DMA transfer.
What is vectored and nonvectored interrupt?
In vectored interrupt, the branch address is assigned to the computer by the source that interrupts the program execution. In nonvectored interrupt, the branch address is stored in a separate portion of memory.
What is priority interrupt?
A priority interrupt is a system that establishes a priority over the various sources to determine which request is to be services first, when two or more interrupts arrive at the same time.
What is polling?
Polling is the procedure used to identify the highest priority source by software. In this all interrupts have a common branching address, and the system takes care of all the interrupts in sequence. This tests the interrupts and the interrupt tested first will get the highest priority.
What is bus transfer?
While DMA communicates directly with memory, a block sequences consisting of a number of memory words is transferred in continuous burst while the DMA controller is master of memory bus. This is good for fast peripherals.
Define Cycle stealing.
Cycle stealing is the process in which the DMA controller transfer one data word at a time, after which it returns control of buses to CPU. The CPU delays the operation for one memory cycle to allow the direct memory I/O transfer to steal one memory cycle.
What is modem?
Modem stands for Modulator-demodulator, which converts the digital signals into audio tones to be transmitted over telephone lines and also converts audio tones from the lines to digital signals for the machines use.
What is half-duplex transmission?
Half-duplex transmission system is one that is capable of transmitting in both directions but data can be transmitted in only one direction at a time.
What is full-duplex transmission?
Full-duplex transmission can send and receive data in both directions simultaneously. ¶ 1:23 AM
When data is being transferred between two units, the units receiving the data responds with another control signal to acknowledge the receipt of the data. This type of agreement between two independent units is called handshaking.
What is synchronous transmission?
Synchronous transmission allows two units to share a common clock frequency and bits are transmitted continuously at the rate dictated by the clock pulse.
What is asynchronous transmission?
The asynchronous transmission allow data transfer between more than two systems, in which they use special bits. The characters send consists of three parts: a start bit, the character bits, and the stop bits. It starts transmission for start bit, and stops on receiving stop bit.
Define baud rate.
Baud rate is defined as the rate at which serial information is transmitted and is equivalent to the data transfer in bits per second.
What are the different modes of data transfer?
Data transfer to and from peripherals could be carried out in one of the following modes: i) Programmed I/O ii) Interrupt initiated I/O iii)Direct memory access
What is programmed I/O mode of data transfer?
Programmed I/O operations are carried out by the result of I/O instructions written to the computer program. Each data item transfer is initiated by an instruction in the program.
What is interrupt?
When an interrupt request signal is issued, the processor suspends the execution of the currently executing program, and starts the execution of the interrupted program. Then, it starts the suspended program. This process is called interrupt.
What is DMA?
Direct memory access allows transfer of data into and out of the memory units through the memory bus, with out the use of CPU. This is called DMA transfer.
What is vectored and nonvectored interrupt?
In vectored interrupt, the branch address is assigned to the computer by the source that interrupts the program execution. In nonvectored interrupt, the branch address is stored in a separate portion of memory.
What is priority interrupt?
A priority interrupt is a system that establishes a priority over the various sources to determine which request is to be services first, when two or more interrupts arrive at the same time.
What is polling?
Polling is the procedure used to identify the highest priority source by software. In this all interrupts have a common branching address, and the system takes care of all the interrupts in sequence. This tests the interrupts and the interrupt tested first will get the highest priority.
What is bus transfer?
While DMA communicates directly with memory, a block sequences consisting of a number of memory words is transferred in continuous burst while the DMA controller is master of memory bus. This is good for fast peripherals.
Define Cycle stealing.
Cycle stealing is the process in which the DMA controller transfer one data word at a time, after which it returns control of buses to CPU. The CPU delays the operation for one memory cycle to allow the direct memory I/O transfer to steal one memory cycle.
What is modem?
Modem stands for Modulator-demodulator, which converts the digital signals into audio tones to be transmitted over telephone lines and also converts audio tones from the lines to digital signals for the machines use.
What is half-duplex transmission?
Half-duplex transmission system is one that is capable of transmitting in both directions but data can be transmitted in only one direction at a time.
What is full-duplex transmission?
Full-duplex transmission can send and receive data in both directions simultaneously. ¶ 1:23 AM
