Nishesh Awale's Blog

S.N. Hardwired Control Unit Micro-programmed Control Unit 1. It is implemented through the use of sequential logic circuit. Its input logic signals are transformed into a set of output logic signals which are control signals. It is implemented through the use of micro-programs. Micro-programs (control information) are organized as a sequence of micro-instructions stored in a special control memory. 2. This design uses a fixed architecture so, it require changes in wiring if the instruction set is modified. It is easy to reconfigure and modify instruction set. 3. It is difficult to build a circuit that satisfies all the operations. It is simple in structure. 4. It has faster mode of operation. It is comparatively slower. 5. It is comparatively expensive. It is cheaper. 6. It is preferred for less number of instruction sets. I...

Have you ever wondered how the microprocessor communicates with the devices connected to it? Well, there are a group of wires (communication path) between microprocessor and its peripherals (and memory) to carry bits which are known as system bus. The system bus performs the following steps to communicate with the peripheral: i.         Identify the peripheral or the memory location (with its address). ii.       Transfer data and instructions in the form of bits. iii.     Provide timing and synchronization signals. According to the above functions, system bus can be classified into three types which are described below: Address Bus: It is a set of wires that is used to transmit address from the microprocessor to its peripheral devices (or memory. It is unidirectional. Each peripheral or memory is identified by its address. This is similar to the postal address of the house. For example...

Modes of data transfer: There are four modes of data transfer which are described below:- 1.       Simple Input and Output:- It is the most primitive form of data transfer. To get the data input from a simple switch such as thermostat into a microprocessor, we have to connect the switch to an input port line and read the switch. Similarly, to output data to a simple display device such as LED, we have to connect the LED buffer or an output port pin and output the logic level required to turn on the light.   2.       Simple strobe I/O:- When a valid data is present on an external device only at certain time, it should be read at appropriate time. For example, input from a keyboard. When a key is pressed, it sends the ASCII code for the pressed key data lines and also sends out a strobe signal on another line to indicate that a valid data is present on the data lines.   3.     ...

Addressing modes of 8085: Each instruction to the microprocessor contains the operation to be performed and the data (operand). The data may be stored anywhere like register, memory and I/O unit. The address of operand can be provided using various ways. The various ways of specifying the operands are called addressing modes i.e. addressing modes specify where the operands are located. 8085 microprocessor has five different addressing modes which are given below:                     i.             Direct addressing                   ii.             Register addressing                 iii.     ...

The Tower of Hanoi is one of the most popular puzzle of the nineteenth century. It consists of three pegs mounted on a board together and consists of disks of different sizes. At first, all the disks are kept on one peg(say peg 1) with the largest peg at the bottom and the size of pegs gradually decreases to the top. Goal:- The goal of this puzzle is to transfer all the disks from one peg to another in order of size, placing the largest one at the bottom. Rule:- The rule of the puzzle is that we can move a disk from one peg to another as long as the disk is never placed on the top of the smaller one. Finding a recurrence relation: Let us consider there are n disks on peg 1. Let, H(n) denotes the number of moves required to solve the puzzle. The initial position is shown in the upper part of the figure. We can transfer the top n-1 disks from peg 1 to peg 3 as shown in the bottom part of the figure. Clearly, this process will take H(n-1) moves. It is because the disks arrangemen...