Transcript EENG 2710 Chapter 0 - UNT College of Engineering

EENG 2710 Chapter 0
Introduction
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Chapter 0 Homework
None
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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
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Computer Generations
• Late 1970’s – 1980’s
– Fourth generation
– Very large scale integration (VLSI) computers
• Now
– Fifth generation ?
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Evolution of Intel Computers
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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.
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Analog Electronics
• Values are continuously variable
between defined values.
• Can have any value within a defined
range.
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Analog Electronics
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Periodic Digital Waveforms
• A periodic digital waveform is a timevarying 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
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Periodic Digital Waveforms
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Aperiodic Digital Waveforms
• An aperiodic digital waveform is a timevarying sequence of logic HIGHs and
LOWs that does not repeat.
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Aperiodic Digital Waveforms
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Waveform Definitions
• Time HIGH (th) is the time a logic signal is
in its HIGH state.
• Time LOW (tl) is the time a logic signal is
in its LOW state.
• Duty cycle is the ratio of the time a logic
signal is HIGH (th) to the period (T).
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Duty Cycle
tl
th
T
Duty Cycle = th/T
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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.
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Pulse Waveforms
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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.
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Pulse Waveform Characteristics
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Pulse Waveform Timing
• Pulse width (tw) 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.
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Pulse Waveform Timing
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Transition of Computer Programs
Into Machine Language
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Digital Electronics
• Values can vary only by distinct, or
discrete, steps.
• Can only have two values.
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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’.
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Digital Logic Levels
5V
3.5 V
0.8 V
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