In this post, find a solved question set on fundamentals of Microprocessor (8085) and Microcontroller.
Microprocessor 8085 fundamental Questions with answers
Explain the features of 8085 in detail.
| Intel 8085 Microprocessor |
| It is a general-purpose 8-bit microprocessor. |
| It contains 40 pins and is available as a dual in-line package (DIP). |
| It has a 16-bit address bus. |
| It has 8-bit data bus. |
| The maximum number of memory locations that can be addressed by this processor is 64 KB. |
| The Clock speed of this microprocessor is 3 MHz |
| It requires a +5 V power supply. |
| The ALU of this processor is called accumulator-oriented ALU. |
| 8085 microprocessor does not support memory segmentation. |
| It does not support pipelining. |
| The ALU of this processor is called accumulator-oriented ALU. |
| Registers B, C, D, E, H, and L are the general purpose registers in the 8085.These are used to store only the data that is being used by the program under execution and the results obtained from it. |
| In 8085, only two registers are 16-bit wide. These are PC (program counter) and SP (stack pointer). |
| It contains about 6500 transistors. |
| It supports external interrupt requests. |
What is an op-code?
An op-code is the first part of the instruction that specifies the operation to be performed.
What is the use of the ALE signal?
Address Latch Enable is a pulse that is provided when an address appears on the AD0-AD7 lines, after which it becomes 0. This signal can be used to enable a latch (74LS373) to save the address bits from the multiplexed address data lines (AD7-AD0), thereby de-multiplexing the address bus and data bus.
What is a microcomputer?
A computer system developed using a basic general-purpose microprocessor is called a microcomputer system. The system consists of CPU, memory, and I/O ports.\
What is the microcontroller and microcomputer?
Microcontrollers contain memory units and I/O ports inside a chip, in addition to the CPU where a microcomputer is a system consisting of CPU, memory, and I/O ports.
What is meant by the wait state?
In 8085 one input signal is there known as the Ready signal, which serves to delay the microprocessor read /write signals until a slow-responding device is ready to send or accept data. If this signal goes low, then the processor is allowed to wait for an integral number of clock cycles until Ready becomes high. The ready signal must be synchronized with the processor clock.
How many interrupts does 8085 have? Mention them.
There are five external hardware interrupts in 8085. They are TRAP, RST7.5, RST6.5, RST5.5 and INTR. Also, there are 8 software interrupts such as RST 0-7.
What is memory mapping or memory-mapped I/O?
It is the technique by which input/output devices are addressed using 16-bit memory addresses and accessed like memory locations, using memory access instructions such as LDA and STA.
What is I/O mapping or peripheral mapped I/O?
It is the technique by which input/output devices are addressed using 8-bit I/O addresses and accessed using IN and OUT instructions.
Give the register organization of 8085.
There are six general-purpose 8-bit registers: Registers B, C, D, E, H, and L. These registers are used to store only the data that is being used by the program under execution and the results obtained from it. These general-purpose registers are user accessible through programs.
There are also special-purpose registers that are dedicated to specific functions. The accumulator (Acc), flag register (F), program counter (PC), and stack pointer (SP) constitute the special registers in the 8085 microprocessor.
What is interfacing?
Interface is the path for communication between two components. Interfacing is of two types, memory interfacing and I/O interfacing.
Memory Interfacing: When we are executing any instruction, the microprocessor needs to access the memory for reading instruction codes and the data stored in the memory.
How does the 8085 processor differentiate memory access (read/write) and I/O access (read/write)?
Using IO/M’ signal pin that indicates whether the read/write operation is being done with respect to the memory or an I/O device. Logic 1 indicates I/O device access and logic 0 indicates memory access. This signal is tri-stated during hold and halt modes.
Why status signals (S1 and S0) are provided in the microprocessor?
Status signals are used to indicate the kind of operation being performed by the microprocessor such as halt, write, read, and fetch.
What are the operations performed by ALU of 8085?
ALU is the circuitry that performs the arithmetic and logical operations. Addition, subtraction, increment, decrement, and comparison are the arithmetic operations possible in the 8085 microprocessor. The possible logical operations are AND, OR, EX-OR, complement, etc.
What is the significance of the HL register pair?
In the 8085 microprocessor, general-purpose registers are all 8-bit registers but they can be handled as 16-bit registers as well. This can be achieved by combining the register pairs B and C, D and E, and H and L to perform 16-bit operations. They are then named as register pairs BC, DE, and HL, respectively.
Among these pairs, HL has special significance. A few memory-related instructions of the 8085 use the HL pair as a memory pointer. For example, in the instruction MOV A, M transfers the content of the memory location to which the HL pair is pointing, to the accumulator.
