2. Digital Logic and Microprocessor (AExE02)

2.1 Digital Logic (AExE0201)

1. Number Systems

   • Binary (Base-2): Uses digits 0 and 1.
   • Octal (Base-8): Uses digits 0-7.
   • Decimal (Base-10): Uses digits 0-9.
   • Hexadecimal (Base-16): Uses digits 0-9 and letters A-F.

2. Logic Levels

   • High (1) and Low (0) represent binary states.
   • Voltage levels define these states (e.g., TTL uses 0V as Low and +5V as High).

3. Logic Gates

   • Basic Gates: AND, OR, NOT.
   • Universal Gates: NAND, NOR.
   • Other Gates: XOR, XNOR.

4. Boolean Algebra

   • Laws: Commutative, Associative, Distributive, Identity, Null, Inverse.
   • Simplification techniques.

5. Sum-of-Products (SOP) Method

   • Logical expressions expressed as a sum (OR) of product terms (AND).

6. Product-of-Sums (POS) Method

   • Logical expressions expressed as a product (AND) of sum terms (OR).

7. Truth Table to Karnaugh Map (K-Map)

   • Simplifies Boolean expressions to reduce circuit complexity.
   • Groups adjacent 1's in a grid to form simplified expressions.

2.2 Combinational and Arithmetic Circuits (AExE0202)

1. Combinational Circuits

   • Output depends only on current inputs.

2. Multiplexer (MUX)

   • Combines multiple inputs into one output based on select lines.

3. Demultiplexer (DEMUX)

   • Splits one input into multiple outputs based on select lines.

4. Decoder and Encoder

   • Decoder: Converts n-bit input into 2ⁿ unique outputs.
   • Encoder: Converts 2ⁿ inputs into n-bit output.

5. Arithmetic Operations

   • Binary Addition and Subtraction using logic gates.
   • Operations on Unsigned and Signed Binary Numbers (e.g., 2’s complement for signed subtraction).

2.3 Sequential Logic Circuit (AExE0203)

1. Flip-Flops

   • RS Flip-Flop: Stores 1-bit data. Basic bistable element.
   • Gated Flip-Flop: Controlled by enable input.
   • Edge-Triggered Flip-Flop: Activates on clock edge.
   • Master-Slave Flip-Flop: Two stages (Master captures input; Slave updates output).

2. Registers

   • Types: Shift Registers (Serial-In-Serial-Out, Serial-In-Parallel-Out, etc.).
   • Applications: Data storage, transfer, and manipulation.

3. Counters

   • Asynchronous Counters: Ripple effect; slower but simpler.
   • Synchronous Counters: All bits change simultaneously; faster and more reliable.

2.4 Microprocessor (AExE0204)

1. Internal Architecture

   • ALU, Control Unit, Registers, Buses (Data, Address, Control).
   • Clock for synchronization.

2. Features

   • Speed (measured in MHz/GHz), word length, power consumption, instruction set.

3. Assembly Language Programming

   • Low-level language close to machine code.
   • Use of mnemonics (e.g., MOV, ADD, SUB).

2.5 Microprocessor System (AExE0205)

1. Memory Device Classification and Hierarchy

   • Types: Primary (RAM, ROM), Secondary (HDD, SSD), Cache, and Registers.
   • Hierarchy: Registers > Cache > RAM > Secondary Storage.

2. I/O and Memory Interfacing

   • Parallel Interface: Transmits multiple bits simultaneously.
   • Serial Interface: Transmits data bit by bit (e.g., UART, SPI).

3. Programmable Peripheral Interface (PPI)

   • Example: Intel 8255 for interfacing peripherals.

4. Transmission Methods

   • Synchronous: Data transferred in sync with clock.
   • Asynchronous: No fixed clock signal; uses start and stop bits.

5. Direct Memory Access (DMA)

   • Bypasses CPU for high-speed data transfer between memory and peripherals.
   • DMA Controllers: Manage data transfer independently.

2.6 Interrupt Operations (AExE0206)

1. Interrupt

   • External or internal signal to CPU requesting attention.

2. Interrupt Service Routine (ISR)

   • Special code executed in response to an interrupt.

3. Interrupt Processing

   • Steps: Save current state, execute ISR, restore state, resume normal operation.