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design of digital systems

intro

intro

system design: looking at sub-systems of systems. From hardware perspective, the components are I/O devices, arithmetic units, memory units, and these devices interconnections
logic design: how should gates be constructed so that binary addition is done? "how should logical building blocks be constructed of the parts of the system?"
circuit design: a gate, flip-flop or other logic building block is made from resistors, diodes, and transistors. Circuit design is combining these latter to form the former. This may be done using computer programs.

we will not worry about circuit design, so in lab and what-not that's just developing the logic behind the circuit. Computer science guys do the logic, EE does the circuits??

Most subsystems in a digital system are "switching circuit"s. I like to think of a "switching circuit" as a transform on input to produce different output. There are two types of switching circuits:

combinational: output not dependent on past values. These are where there is gates only (and,or,nand,nor). There are inputs and outputs.
sequential circuit: output is dependent on past values
the basic elements used in the design of sequential circuits are flip-flops. Flip-flops can be interconnected with gates to form counters and registers. There are other kinds of sequential devices all described in

Combinational circuits are designed of logic gates so that the necessary addition and subtraction are performed to produce the desired output. The math is based on boolean algebra. Boolean algebra is used to decide how to use inputs to transform that into outputs.

book: fundamentals of logic design

author: Charles Roth

units 1-4 deal with studying the logic background needed to discuss circuits. Unit 5-6 use other simplification methods, Karnaugh map and Quine-McCluskey procedure.

binary numbers are used to describe digital systems because usually the components have only two discrete states.

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