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8085 microprocessor doubts

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vasanth kumar

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hello,
in microprocessor 8085, lower 8 bits of address bus is multiplexed with 8 bit bidirectional data bus in order to reduce the number of pins. but why there are seperate pins for read and write. why not they could not be given as read and write in a single pin by seperating them with active high and low signals respectively.
thanks......
 

vasanth kumar said:
hello,
in microprocessor 8085, lower 8 bits of address bus is multiplexed with 8 bit bidirectional data bus in order to reduce the number of pins. but why there are seperate pins for read and write.
Click to expand...

Good question, the reason is simply "styles".
Many memories have (had) separate lines for R/W signal, however , many other devices have a single line for R/W operation.
The reason for separate R/W lines is, in my opinion, a good tradeoff for the capability of driving both kind of devices.
 
Its just a old kind of processor, and it was designed based on the usage of the peripherals then.
There are many kind of updates after. At that time they still haven't developed Micro-controller completely yet.
 

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