So that the processor can both read and write data.
The address bus is unidirectional becos address information is always given by microprocessor to i/o devices. The data bus is bidirectional bcos it takes the data from other devices & also give the data to other i/o devices
A data should be either WRITTEN to a memory or should be READ from a memory (both direction)and so the data bus is bidirectional.
A bus in this context is a data route which can carry data in both directions.
A data bus is bidirectional because the processor needs it to both read and write. Also, in the case of the 4004, the data bus was tri-multiplexed with the 12 bit address bus and the 8 bit opcode bus.
The control bus is a unidirectional bus because it can receive the data from any kind of inputs and send back the output. This whole process is done by the data buses.
there are mainly 3 buses are there in 8085. They are: Address bus :-Used to carry address Data bus :- Used to carry data Control bus :-Used to carry signals such as control and timing signals
since data can be read /write from/to the microprocessor, hence data bus is bidirectional. if data is required read from microprocessor then it will be pointing to a memory location by the address bus, by indicating which location data its required to read. similarly to write a data to a location, again the microprocessor will be to that particular location by holding that address in address bus. hence it will be unidirectional.
The data bus of 8085 is 8 bit.Its operating frequency is 3.03 Mhz.Address bus is 16 bit. The data bus of 8086 is 16 bit.Its operating sfrequency is 5 MHZ.Address bus is 20 bit.
The data bus is used to read or write (hence bi-directional) to the data location selected by the address written on the address bus. You only need to write (one-way) to the address bus to select the data location. It does not make sense to read from the address bus.
The Intel 8085 is an 8 bit microprocessor created in 1977.The Intel 8086 is a 16 bit microprocessor created in 1978. The 8086 was the first chip to start the x86 architecture family.8085 contains 16-bit address bus and 8-bit data bus8086 contains 20-bit address bus and 16-bit data bus..In 8085 the clock speed is 3MHZwhere as in 8086 the clock speed is 5MHZ.there are two differences btw 8085&80861. 8086 has 6 byte queue but 8085 has 4 byte queue2. 8086 has 16 bit data bus where as 8085 has 8 bit data bus
The higher order address bus is not multiplexed with data bus of 8085 because that is the way Intel designed the processor. Besides, the data bus is only 8 bits and the address bus is 16 bits. If you were to multiplex the whole address bus on the data bus, you would need two T1 (ALE) states, and that would be excess logic. Back to the original answer - that is simply the way Intel designed the processor.
The data bus of 8085 is 8 bit and so it will read or write 8 bits simultaneously.So it is Parallel Devise