In this tutorial, we are going to learn about Best Tutorial on 8257 DMA Controller
- It is a hardware device which allows I/O devices to directly access memory with less participation of the processor and it needs the same old circuits of an interface to communicate with the CPU, input and output devices.
There are two types of DMA Males-
- Burst Mode
- Cycle stealing. Technique
- The DMA controller are the s/o derive does not withdrew hold resists until and unless the data is completely transferred. Therefore the processor interfered much. When the data is completely transferred the controller of bores is t even back by the pressers
Cycle Stealing Mode-
- A serve of cycle are set such that byte or n-bytes of Data are transferred in a particular sequencer. The processor is interrupted only when there is need of data transfer. Therefore the time of the processor is efficiently used.
Difference b/w RISC and CISC-
|Reduced instruction set computer||Complex Instruction set computer|
|Less Instructors||More Instruction|
|Less addressing Mode||More addressing Mode|
|Faster than CISC||Slower|
|More General Purpose Register (GPR)||Less GPR ‘s|
|Instruction execute in one clock||More than one clock|
|Register to register transfer only||Register to register , memory I/0|
|Load store instruction only||Load, Store 4 others|
|More cache memory||Less cache memory|
|Control signals are generated by hard work.||Control signal are generated by micro electronic circuitry is used Sun’s Sparse power PC by micro instruction|
|Sun’s Sparse power PC||of In tel 80386, 486 Pentium Pro Motorola M68000 M68020|
- It is given in terms of memory access time (TA)
- TA → Time delay b/w address placed on address bus and data reserved on the data bus.
Bus Contention- (Traffic jam)
This occurs when one device is being deselected and other being selected.