1. 1 EENG 2710 Chapter 0 Introduction

2. 2 Chapter 0 Homework None

3. 3 Computer Generations 1940’s - Early 1950’s –Labeled first generation –Vacuum tube computers Late 1950’s –Second generation –Transistor computers 1960’s – Early 1970’s –Third generation –Integrated Circuit computers

4. 4 Computer Generations Late 1970’s – 1980’s –Fourth generation –Very large scale integration (VLSI) computers Now –Fifth generation ?

5. 5 Evolution of Intel Computers

6. 6 Analog vs. Digital Analog: –A way of representing a physical quantity by a proportional continuous voltage or current. Digital: –A way of representing a physical quantity in discrete voltage steps.

7. 7 Analog Electronics Values are continuously variable between defined values. Can have any value within a defined range.

8. 8 Analog Electronics

9. 9 Periodic Digital Waveforms A periodic digital waveform is a time- varying sequence of logic HIGHs and LOWs that repeat over some period of time. Period (T) is the time required for the pattern to repeat. Frequency (f) is the number of times per second a signal repeats and is the reciprocal of period. f = 1/T

10. 10 Periodic Digital Waveforms

11. 11 Aperiodic Digital Waveforms An aperiodic digital waveform is a time- varying sequence of logic HIGHs and LOWs that does not repeat.

12. 12 Aperiodic Digital Waveforms

13. 13 Waveform Definitions Time HIGH (t h ) is the time a logic signal is in its HIGH state. Time LOW (t l ) is the time a logic signal is in its LOW state. Duty cycle is the ratio of the time a logic signal is HIGH (t h ) to the period (T).

14. 14 Duty Cycle thth tltl T Duty Cycle = t h /T

15. 15 Pulse Waveforms A pulse is a momentary variation of voltage from one logic level to the opposite level and back again. Amplitude is the voltage magnitude of a pulse. Edge is the part of a pulse representing the transition from one logic level to the other.

16. 16 Pulse Waveforms

17. 17 Pulse Waveform Characteristics Rising edge is the transition from LOW to HIGH. Falling edge is the transition from HIGH to LOW. Leading edge is the earliest transition. Falling edge is the latest transition.

18. 18 Pulse Waveform Characteristics

19. 19 Pulse Waveform Timing Pulse width (t w ) is the time from the 50% point of the leading edge to the 50% point of the trailing edge. Rise time is the time from 10% to 90% amplitude of the rising edge. Fall time is the time from 90% to 10% amplitude of the falling edge.

20. 20 Pulse Waveform Timing

21. 21 Transition of Computer Programs Into Machine Language

22. 22 Digital Electronics Values can vary only by distinct, or discrete, steps. Can only have two values.

23. 23 Digital Logic Levels Logic HIGH is the higher voltage and represented by binary digit ‘1’. Logic LOW is the lower voltage and represented by binary digit ‘0’.

24. 24 Digital Logic Levels 0.8 V 3.5 V 5 V