# Department of Computer Science and Technology

Course pages 2019–20

Subsections

## Paper 2: Digital Electronics

This course is not taken by NST students.

Lecturer: Dr I.J. Wassell

No. of lectures and practical classes: 12 + 7

Suggested hours of supervisions: 3

This course is a prerequisite for Operating Systems and Computer Design (Part IB), ECAD and Architecture Practical Classes (Part IB).

### Aims

The aims of this course are to present the principles of combinational and sequential digital logic design and optimisation at a gate level. The use of n and p channel MOSFETs for building logic gates is also introduced.

### Lectures

• Introduction. Semiconductors to computers. Logic variables. Examples of simple logic. Logic gates. Boolean algebra. De Morgan’s theorem.

• Logic minimisation. Truth tables and normal forms. Karnaugh maps. Quine-McCluskey method.

• Combinational logic design: further considerations. Multilevel logic. Gate propagation delay. An introduction to timing diagrams. Hazards and hazard elimination. Other ways to implement combinational logic.

• Introduction to practical classes. Prototyping box. Breadboard and Dual in line (DIL) packages. Wiring. Use of oscilloscope.

• Sequential logic. Memory elements. RS latch. Transparent D latch. Master-slave D flip-flop. T and JK flip-flops. Setup and hold times.

• Sequential logic. Counters: Ripple and synchronous. Shift registers.

• Synchronous State Machines. Moore and Mealy finite state machines (FSMs). Reset and self starting. State transition diagrams. Elimination of redundant states.

• Further state machines. State assignment: sequential, sliding, shift register, one hot. Implementation of FSMs.

• Introduction to microprocessors. Microarchitecture, fetch, register access, memory access, branching, execution time.

• Electronics, Devices and Circuits. Current and voltage, resistance, basic circuit theory, the potential divider. Solving non-linear circuits. N and p channel MOSFETs and n-MOSFET logic, e.g., n-MOSFET inverter. Switching speed and power consumption problems in n-MOSFET logic. CMOS logic. Logic families. Noise margin. Analogue interfacing and operational amplifiers. [3 lectures]

### Objectives

At the end of the course students should

• understand the relationships between combination logic and boolean algebra, and between sequential logic and finite state machines;

• be able to design and minimise combinational logic;

• appreciate tradeoffs in complexity and speed of combinational designs;

• understand how state can be stored in a digital logic circuit;

• know how to design a simple finite state machine from a specification and be able to implement this in gates and edge triggered flip-flops;

• understand how to use MOSFETs to build digital logic circuits.

• understand the effect of finite load capacitance on the performance of digital logic circuits.

• understand basic analogue interfacing.