ECE 3110: Introduction to Digital Systems Introduction (Contd.)

2 Previous class Summary Digital devices Digial vs analog Why digial

3 Analog vs. Digital Analog: time-varying signals Take any value across a continuous range of voltage, current or whatever metric Digital: SAME. But pretend they don’t. Modeled as taking only one of two discrete values at any time 0/1, LOW/HIGH, FALSE/TRUE,…

4 Digital Logic Binary system -- 0 & 1, LOW & HIGH, negated and asserted. Basic building blocks -- AND, OR, NOT

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6 Digital Devices Integrated Circuits that operate on Digital Data are in 95% of every electrical powered device in the U.S. The theory of operation of these devices form a basis for many other courses in the EE/CS/COEN curriculum The job market for engineers and computer scientists with Digital Design skills is at an all time high and will continue growing.

7 Analog versus Digital Analog Voltage meter Digital Voltage meter About 100

8 Analog offers Continuous Spectrum Digital offer distinct Steps

9 Analog has Ambiguity Digital has only one interpretation Analog Clock 1:56 pm Digital Clock About 2:00 1:50 1:56

10 Electronic aspect of digital design Digital abstraction Range Noise margin Invalid range Specifications

11 Software aspect of digital design Digital design need not involve any software tools. But: modern design, software tools are essential. Examples: Schematic entry, HDLs (platform compilers, simulators, synthesis tools),simulators, test benches, timing analyzers and verifiers, word processors, high-level languages, CAD

12 Integrated Circuits (IC) A collection of one or more gates fabricated on a single silicon chip. Wafer, die Small-scale integration (SSI): 1-20 DIP: dual in-line-pin package Pin diagram, pinout MSI: gates LSI: ,000 VLSI: >100,000, 50million (1999)

13 Integrated Circuits (IC) Copyright © 2001 Fine Arts Photographics

14 DIP pinout

15 Programmable Logic Device (PLD) ICs which Logic function can be programmed after manufacture. 2-level AND-OR gates using user- programmable connections PLAs: programmable Logic Arrarys. PALs: programmable array logic devices Programmable logic devices (PLDs) CPLD: complex PLD FPGA: Field-Programmable Gate Array

16 CPLD vs FPGA

17 Application-Specific ICs (ASIC) Semicustom IC: chips designed for a particular, limited product/application Reducing chip count, size, power consumption Higher performance. NRE: nonrecurring engineering cost Standard cells: library Gate arrary: an IC with internal structure as an array of gates, unspecified interconnection

18 Printed-Circuit Board PCB or PWB (printed-wiring board) Mount Ics so that an IC can connect to other Ics in a system. SMT: Surface-mount technology MCM: multichip modules: high speed and density.

19 Digital Design Levels Many representations of digital logic Device Physics and IC manufacturing Moore’s Law [1965, Gordon Moore]: Transistor level --->Logic design, functional building blocks The number of transistors per square inch in an IC doubles every year [18months].

20 Digital Design Levels Transistor-level circuit diagrams Example: Multiplexor

21 Truth tables Gate-level Logic diagrams

22 Prepackaged building blocks, e.g. multiplexer Equations: Z = S  A  + S  B

23 Various hardware description languages ABEL VHDL

24 Summary Electronics/sw aspects of digital design Integrated Circuits (wafer,die,SSI,MSI,LSI,VLSI) PLDs: PLAs,PALs,CPLD,FPGA ASIC Digital design levels

25 Next… HW#1 HW #1: Assign 06/04/2004: Work Wakerly problems 1.3, 1.5, 1.6 Due: 06/09/2004 Number systems Reading: Wakerly chapter 2