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A 16-bit uP operates on instructions and data in 16-bit quantities. Therefore the databus is 16-bits. A 16-bit uP may also operate on larger quantities of data, however multiple CPU registers must be concatenated in order to maintain the data element in the uP register space. The data is always delivered to the processor 16 bits at a time. The amount of memory which it can address is a separate issue---the address bus size is totally distinct from the data bus size. The data bus determines how much memory may be delivered to the uP per cycle. The address bus size determines how much physical memory may actually be accessed by the uP. Therefore it is variable depending on how much memory is available. Typical systems today have 32-bit address busses which limit addressable memory to 4Gigabytes. (2^32) = 4G.
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What is bus in 8085?
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
What is the size of address bus in 8086?
The address bus in the 8085 is 16 bits wide.
Why is data bus bidirectional but address bus unidirectional?
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
Why higher order address bus not multiplexed with data bus of 8085?
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.
What is the address space in a system with 16-bit addresses?
It depends on the size of the address bus, which is often different than the size of the data bus.If the address bus were 8 bits, then you could address 256 locations.If the address bus were 16 bits, such as in the 8085, then you could address 65,536 locations.If the address bus were 20 bits, such as in the 8086/8088, then you can address 1,048,576 locations.
How many address bits does 8085 have?
The 8085 has a 16 bit address bus.
What is the need of ale signal in 8085?
The ALE signal on the 8085 is Address Latch Enable. When ALE is true, the data bus contains the low order address information for the current bus cycle. External hardware, i.e. latches, are expected to follow the data bus when ALE is true. At the point where ALE goes false, at approximately the rising edge of CLK, the latches are expected to latch and hold the data bus, presenting it to the outside world as the low order address bus.
Why does microprocessor 8086 has 16 data bus and 20 address bus why aren't they equal?
The 8086 has 16 data bus lines and 20 address bus lines because that is how Intel designed it. They wanted a processor that was more powerful than the 8085, which has an 8 bit data bus and a 16 bit data bus, so they increased both bus sizes accordingly.
What is the difference between the Intel 8085 and the Intel 8086?
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
Size of 8086 address bus?
The 8086/8088 has an internal 20-bit address bus and 16-bit data bus. Externally, the address bus is 20-bits, and the data bus is 16-bits for the 8086 and 8-bits for the 8088.The data bus in the 8086 is 16 bits in size, while the address bus is 20.
How are the data bus and address bus are demultiplexed?
The data and address buses are multiplexed in order to save pin count on the chip. In the first clock cycle of a read or write cycle, the address is emitted on the address/data bus. The ALE signal is used to strobe the address, after which the address/data bus becomes the data bus. External logic is expected to strobe the address at the trailing edge of ALE. ALE is generated directly by the 8085, and by the 8086/8088 in minimum mode. In maximum mode in the 8086/8088, ALE is generated by the 8288 Bus Controller.
Why data and address buses are tristated in 8085?
In the general case, a bus is tristated to allow more than one source to drive it. This can be the simple case of a bi-directional bus, or the more complex case of a multi-master bus configuration. In the 8085, the address bus is tristated when a HOLD/HLDA sequence is in process, allowing another bus master to control the bus. The data bus is tristated for the same reason, and also to allow bi-directional data flow (read vs write) to occur.
