Isolated I/O and Memory Mapped I/O

List Out The Differences Between Isolated I/o And Memory Mapped I/o.?

Jeyamari
30 Jul 2018
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Mohammad
30 Jul 2018

Memory mapped I/O and Isolated I/O As a CPU needs to communicate with the various memory and input-output devices (I/O) as we know 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 : 01:Separate set of address, control and data bus to I/O and memory. 02:Have common bus (data and address) for I/O and memory but separate control lines. 03:Have common bus (data, address, and control) for I/O and memory. In first case it is simple because both have different set of address space and instruction but require more buses. Isolated I/O &ndash; Then we have Isolated I/O in which we Have common bus(data and address) for I/O and memory but separate read and write control lines for I/O. So when CPU decode instruction then if data is for I/O then it places the address on the address line and set I/O read or write control line on due to which data transfer occurs between CPU and I/O. As the address space of memory and I/O is isolated and the name is so. The address for I/O here is called ports. Here we have different read-write instruction for both I/O and memory. Memory Mapped I/O &ndash; In this case every bus in common due to which the same set of instructions work for memory and I/O. Hence we manipulate I/O same as memory and both have same address space, due to which addressing capability of memory become less because some part is occupied by the I/O. Differences between memory mapped I/O and isolated I/O &ndash; ISOLATED I/O &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; MEMORY MAPPED I/O *Memory and I/O have seperate address space &nbsp; *Both have same address space *All address can be used by the memory &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; *Due to addition of I/O addressable memory become less for memory *Separate instruction control read and&nbsp; write operation in I/O and Memory &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; *Same instructions can control both I/O and Memory *In this I/O address are called ports. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; *Normal memory address are for both *More efficient due to seperate buses &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; *Lesser efficient *Larger in size due to more buses&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;*Smaller in size

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Memory mapped I/O and Isolated I/O
As a CPU needs to communicate with the various memory and input-output devices (I/O) as we know 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 :

01:Separate set of address, control and data bus to I/O and memory.
02:Have common bus (data and address) for I/O and memory but separate control lines.
03:Have common bus (data, address, and control) for I/O and memory.
In first case it is simple because both have different set of address space and instruction but require more buses.

Isolated I/O –
Then we have Isolated I/O in which we Have common bus(data and address) for I/O and memory but separate read and write control lines for I/O. So when CPU decode instruction then if data is for I/O then it places the address on the address line and set I/O read or write control line on due to which data transfer occurs between CPU and I/O. As the address space of memory and I/O is isolated and the name is so. The address for I/O here is called ports. Here we have different read-write instruction for both I/O and memory.

Memory Mapped I/O –
In this case every bus in common due to which the same set of instructions work for memory and I/O. Hence we manipulate I/O same as memory and both have same address space, due to which addressing capability of memory become less because some part is occupied by the I/O.

Differences between memory mapped I/O and isolated I/O –

ISOLATED I/O MEMORY MAPPED I/O
*Memory and I/O have seperate address space *Both have same address space
*All address can be used by the memory *Due to addition of I/O addressable memory become less for memory
*Separate instruction control read and
write operation in I/O and Memory *Same instructions can control both I/O and Memory
*In this I/O address are called ports. *Normal memory address are for both
*More efficient due to seperate buses *Lesser efficient
*Larger in size due to more buses *Smaller in size

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