Design of ALU ALU forms one of the important block of a digital computer. It is a multi-operation, combinational circuit. Number of operations supported depend on the complexity of its design. It takes two numbers of n-bit wide as input, performs an operation depending on the function select inputs and produces the output Fn, It also has carry-in input to provide additional functionality and carry-out line which can be part of the result or can act as input to the next stage when the functionality is extended to accommodate numbers with more number of bits. If an ALU has k function select lines, then it will have 2k operations. Figure-1 shows the block diagram of an ALU. Modular design technique can be

# Digital Logic and Computer Design

The course on Digital Logic and Computer Design is designed for the students of B.Tech Computer Science and Engineering. It covers topics on Number systems, Boolean Algebra, Binary arithmetic, Simplification of Boolean functions, combinational and the sequential circuits, basic computer organization, computer arithmetic, input-output organization, modes of data transfer and the memory subsystem

# Micro-Operations

Introduction Internal organization of a digital system is defined by sequence of micro-operations it performs on the data stored in its registers. The general purpose digital computer is capable of executing various micro-operations and, in addition, can be instructed as to what specific sequence of operations it must perform. Now we define basic terminologies: A program is a set of instructions that specify the operations, operands, and the sequence by which the processing has to occur. A computer instruction is a binary code that specifies a sequence of micro-operations for the computer. Instruction code is a group of bits that instruct the computer to perform a specific operation that is usually divided into parts and the most basic part is the operation

# Digital Computer Organization and controls

Stored Program organization The simplest way to organize a computer is to have one processor register and an instruction code format with two parts. The first part specifies the operation to be performed and the second specifies the address. The memory address tells the control where to find the operand in the memory. This operand is read from the memory and used as data to be operated on together with the data stored in the processor register. Figure below depicts this type of computer organization. Instructions are stored in one section of the memory and the operands or data in another. For example if we have a 4K x16 memory unit, it will require 12-bit address to access each memory word. The instruction

# Logic Gates

LOGIC GATES In this post we are going to learn about all the logic gates, their symbols, truth table and the logic equations. The different logic gates that will be covered are: 1. BUFFER 2. NOT 3. OR 4. AND 5. NAND 6. NOR 7. XOR 8. XNOR Binary Values: When only two possible states are to

# Boolean Postulates and Theorem

BOOLEAN POSTULATES and THEOREM Boolean algebra was introduced by George Boole in 1854. Boolean algebra is used to perform binary and logical operations and differs in this respect from the ordinary algebra. Postulates of Boolean Algebra 1. Identity Law : A + 0 = A A.1 = A 2. Commutative Law: (A+B) = (B+A) A.B = B.A 3. Associative Law: A + (B + C) = (A + B) + C A.(B.C) = (A.B).C 4. Distributive Law: A . (B + C) = A.B + A.C A + (B.C) = (A + B). (A + C) 5. Complement Law: A+A’ = 1 A.A’ = 0 Boolean Algebra Theorems 1. Duality Theorem: It states that we can derive a Boolean relation from another Boolean relation by just : i. Changing the ‘.’ With a ‘+’