16Bit Microprocessor : 8086

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Features of 8086
- 8086 is a 16bit processor. It’s ALU, internal registers works with 16bit binary
word
- 8086 has a 16bit data bus. It can read or write data to a memory/port either 16bits
or 8 bit at a time
- 8086 has a 20bit address bus which means, it can address upto 220 = 1MB memory
location
- Frequency range of 8086 is 6-10 MHz
Data Read/Write process from /To Memory

Word Read
- Each of 1 MB memory address of 8086 represents a byte wide location
- 16bit words will be stored in two consecutive Memory location
- If first byte of the data is stored at an even address , 8086 can read the entire

word in one operation.
o For example if the 16 bit data is stored at even address 00520H is 2607
MOV BX, [00520]
8086 reads the first byte and stores the data in BL and reads the 2nd byte
and stores the data in BH
BL
(00520)
BH
(00521)
- If the first byte of the data is stored at an ODD address, 8086 needs two operation
to read the 16 bit data
o For example if the 16 bit data is stored at even address 00521H is F520
MOV BX, [00521]
In first operation , 8086 reads the 16 bit data from the 00520 location and
stores the data of 00521 location in register BL and discards the data of
00520 location