Intel 8086-Intel first 16 bit micro-processor was developed using HMOS technology containing 29,000 transistors housed in 40 pin DIP packages.It can directly address 1 MB memory space .It uses segmented memory.The most interesting feature of the 8086 is that it prefetches up to 6 instruction byte from the memory and queues them in order to speed up the instruction execution .A variant of the 8086 ,the 8088 has 8 line rather 16 lines external bus.The 8088 launched in 1979 was incorporate in the IBM PC's launched in 1982.
8086:8086 operate with single +5v power supply .It does not have on chip clock generator .The 8284 clock generator chip generate the clock for the 8086 .Its instruction execution time varies from 2 clock cycle to 30 clock cycles.The 8086 and 8088 are similar in organization and identical in instructions.The 8088 became very popular only because it found its birth in PC's.For software designers 8086 and 8088 are identical.8088 are slower execution than 8086 for same clock speed.
The 8086 has 20 bit address lines.The AD15 to AD0 are 16 bit multiplexed address and data buses and 4 separate address lines A19-A16.The most significant address A19 -A16 and the 16 bit least significant address AD15-AD0 make it the 20 bit address.A 16 bit word is send or received on AD15-AD0.The least significant byte of the word is transmitted on AD7-AD0 and most significant bit through AD15-AD8.Either AD7-AD0 or AD15-AD8 can be used to transfer only 1 byte or not the complete word.
Most of the instruction of the 8086 operate both on byte and word operands.
Labels: Intel Micro-Processors
