Users Also Read
MCQ's Search Engine
Electrical Engineering
Mechanical Engineering
Civil Engineering
Automobile Engineering
Chemical Engineering
Computer Engineering
Electronics Engineering
Medical Science Engg
All Engineering Dictionary Terms
Definition of "memory mapped I/O" |
Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) (which is also called isolated I/O) are two complementary methods of performing input/output between the CPU and peripheral devices in a computer. An alternative approach is using dedicated I/O processors commonly known as channels on mainframe computers that execute their own instructions.Memory-mapped I/O uses the same address bus to address both memory and I/O devices – the memory and registers of the I/O devices are mapped to address values. So when an address is accessed by the CPU, it may refer to a portion of physical RAM, but it can also refer to memory of the I/O device. Thus, the CPU instructions used to access the memory can also be used for accessing devices. Each I/O device monitors the CPU's address bus and responds to any CPU access of an address assigned to that device, connecting the data bus to the desired device's hardware register. To accommodate the I/O devices, areas of the addresses used by the CPU must be reserved for I/O and must not be available for normal physical memory. The reservation might be temporary the Commodore 64 could bank switch between its I/O devices and regular memory or permanent. / I/O scheme in which I/O control and data “registers” and buffers are locations in main memory and are manipulated through the use of ordinary instructions. Computers with this architecture do not have specific I/O commands. Instead, devices are treated as memory locations. This simplifies the structure of the computer’s instruction set. |
Please type any word or choose alphabet below... |
A
B
C
D
E
F
G
H
I
J
K
L
M N O P Q R S T U V W X Y Z 1 2 3 4 5 6 7 8 9 0 |