Computer hardware
- 1. COMPUTER HARDWARE CSC 2314 ALQALAM UNIVERSITY KATSINA BY UMAR DANJUMA MAIWADA
- 2. ANALOG AND DIGITAL COMPUTERS Signals: Analog or digital •Analog signal has infinitely many levels of intensity (infinitely many values, continuous values) over a period of time. •Digital signal has only a limited number of defined values (discrete values) say 0, 1.
- 3. ANALOG COMPUTERS • Analog signals are directly measurable quantities. • Analog data: human voice, chirping of birds etc. , converted to— Analog or digital signals. • Analog computers can have a very wide range of complexity.
- 4. Analog signal •If a signal does not change at all, its frequency is zero. •If it changes instantaneously, its frequency is infinite. •An analog signal is best represented in the frequency domain.
- 6. Components of Analog Computers • Analog computers often have a complicated framework, but they have, at their core, a set of key components which perform the calculations. • Key electrical/electronic components might include: Precision resistors and capacitors operational amplifiers Multipliers potentiometers fixed-function generators.
- 7. DIGITAL COMPUTER • Digital signals only have two states. For digital computer, we refer to binary states, 0 and 1. • Digital data: data stored in computer memory, converted to—Analog or digital signals. • A digital computer is one that runs on numbers /other data made up from binary - everything breaks down into 1 and 0s. These 1s and 0s may be gained by measuring, for example, whether the voltage of an electrical current travelling through the computer is high or low.
- 8. Digital Signals •1 can be encoded as positive voltages say 5 volts, 0 as zero voltage (or negative voltages say –5volts) •Most digital signals are aperiodic. Thus we use •Bit interval (instead of period): time required to send one bit = 1/ bit rate. •Bit rate (instead of frequency):number of bits per second.
- 10. DIGITAL-TO-ANALOGUE AND ANALOGUE-TO- DIGITAL CONVERSION • Data Converters • There are several different types of ADCs, some of which contain a digital-to analogue converter (DAC) that converts a digital number to the equivalent analogue signal. • A digital to analogue converter (DAC) converters a digital input represented as a binary number to an analogue voltage (or current) that is proportional to the value of this input.
- 11. Reason for ADC • Microprocessors can only perform complex processing on digitized signals. • When signals are in digital form they are less susceptible to the deleterious effects of additive noise. • ADC Provides a link between the analog world of transducers and the digital world of signal processing and data handling.
- 12. Types of A/D Converters • Dual Slope A/D Converter • Successive Approximation A/D Converter • Flash A/D Converter • Delta-Sigma A/D Converter
- 13. D/A Converters • The simplest way of convert a digital input word into a corresponding analogue voltage is to use an op-amp as a summing amplifier with a weighted resistor ``ladder''. • One potentially useful modification to this basic architecture is to use a variable voltage source, possibly formed by a second DAC, to create a variable reference voltage. • The analogue output signal is then proportional to the product of the variable reference voltage and the input binary number; this type of device is usually known as a multiplying DAC or MDAC.
- 15. A/D converters (ADCs) • Analogue to Digital (A/D) conversion is the process whereby an analogue signal is converted into a corresponding binary number, the digital output. • The ideal relationship between the analogue input and the digital output for a 3-bit A/D converter. • The input analogue values are quantized by dividing the continuous analogue input range into 8 discrete steps or code ranges.
- 17. Examples D/A and A/D Signals •Analog data as analog signal: Human voice from our houses to the telephone exchange. •Analog data as digital signal: most of the systems today: Say Human voice, images sent on digital lines. New telephone system (digital exchanges) •Digital data as analog signal: computer data sent over internet using analog line. Say telephone line (say our house to the exchange) •Digital data as digital signal: say from one digital exchange to another
- 18. Comparison of Analog and digital signals
- 20. References • German computer museum with still runnable analog computers (http://technikum29.de/en/computer/analog) • Analog computer basics (http://www.play-hookey.com/analog/) • Lecture 20: Analog vs Digital (http://www.yorku.ca/sasit/sts/sts3700b/lecture20a.html) (in a series of lectures on "History of computing and information technology") • Analog computer trumps Turing model (http://www.eetimes.com/story/OEG19981103S0017) • Jonathan W. Mills's Analog Notebook