Anna University, Chennai
EC2304 – MICROPROCESSORS AND MICROCONTROLLERS UNIT I
INTRODUCTION TO 8 BIT AND 16 BIT MICROPROCESSORS – H/W ARCHITECTURE
1. What is Microprocessor ?
It is a program controlled semiconductor device (IC}, which fetches, decode and executes instructions.
2. What are the basic units of a microprocessor ?
The basic units or blocks of a microprocessor are ALU, an array of registers and control unit.
3. What is Software and Hardware?
The Software is a set of instructions or commands needed for performing a specific task by a programmable device or a computing machine. The Hardware refers to the components or devices used to form computing machine in which the software can be run and tested.
Without software the Hardware is an idle machine.
4. What is assembly language?
The language in which the mnemonics (short -hand form of instructions) are used to write a program is called assembly language. The manufacturers of microprocessor give the mnemonics.
5. What are machine language and assembly language programs?
The software developed using 1's and 0's are called machine language, programs. The software developed using mnemonics are called assembly language programs.
6. What is the drawback in machine language and assembly language, programs?
The machine language and assembly language programs are machine dependent. The programs developed using these languages for a particular machine cannot be directly run on another machine
7. Define bit, byte and word.
A digit of the binary number or code is called bit. Also, the bit is the fundamental storage unit of computer memory. The 8-bit (8-digit) binary number or code is called byte and 16-bit
binary number or code is called word. (Some microprocessor manufactures refer the basic data size operated by the processor as word).
8. What is a bus?
Bus is a group of conducting lines that carries data, address and control signals.
9. Why data bus is bi-directional?
The microprocessor has to fetch (read) the data from memory or input device for processing and after processing, it has to store (write) the data to memory or output device. Hence the data bus is bi-directional.
10. Why address bus is unidirectional?
The address is an identification number used by the microprocessor to
identify or access a memory location or I / O device. It is an output signal from the processor. Hence the address bus is unidirectional.
11. What is the function of microprocessor in a system?
The microprocessor is the master in the system, which controls all the activity of the system. It issues address and control signals and fetches the instruction and data from memory. Then it executes the instruction to take appropriate action.
12. Why interfacing is needed for 1/0 devices?
Generally I/O devices are slow devices. Therefore the speed of I/O devices does not match with the speed of microprocessor. And so an interface is provided between system bus and I/O devices.
13. What is the difference between CPU bus and system bus?
The CPU bus has multiplexed lines but the system bus has separate lines for each signal. (The multiplexed CPU lines are demultiplexed by the CPU interface circuit to form system bus).
14..What does memory-mapping mean?
The memory mapping is the process of interfacing memories to microprocessor and allocating addresses to each memory locations.
15..What is interrupt 1/0?
If the 1/0 device initiate the data transfer through interrupt then the 1/0 is called interrupt driven 1/0.