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Differentiate between I/O mapped I/O and Memory mapped I/O of 8086.

written 6.1 years ago by meghalikalyankar • 2.3k

•   modified 5.1 years ago

microprocessors and peripherals

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written 6.1 years ago by meghalikalyankar • 2.3k

Sr. No.	I/O Mapped I/O	Memory Mapped I/O
1.	I/O device is treated as an I/O device and hence given an I/O address.	I/O device is treated like a memory device and hence given a memory address.
2.	I/O device has an 8 or 16 bit I/O address.	I/O device has a 20 bit Memory address.
3.	I/O device is given IOR# and IOW# control signals	I/O device is given MEMR# and MEMW# control signals
4.	Decoding is easier due to lesser address lines	Decoding is more complex due to more address lines
5.	Decoding is cheaper	Decoding is more expensive
6.	Works faster due to less delays	More gates add more delays hence slower
7.	Allows max 2^16 = 65536 I/O devices	Allows many more I/O devices as I/O addresses are now 20 bits.
8.	I/O devices can only be accessed by IN and OUT instructions.	I/O devices can now be accessed using any memory instruction.
9.	ONLY AL/ AH/ AX registers can be used to transfer data with the I/O device	Any register can be used to transfer data with the I/O device
10.	Popular technique in Microprocessors.	Popular technique in Microcontrollers

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