The Elements of Computing System Notes

Hardware

Hello, World Below

Nand to Tetris

Abstraction and Implementation

Abstraction describes what the module does, and implementation describes how it does it.

The RAM contains billions of registers, yet any of them can be accessed directly.

The RAM storage and direct-access capabilities will be relized using registers and multiplexers.

Methodology

The Road Ahead

1 Boolean Logic

Elementary logic gates.

Nand, Not, And, Or, and Xor.

Multiplexer and Demultiplexer.

1.1 Boolean Algebra

A Boolean function is a function that operates on binary inputs and returns binary outputs.

The name of the Nand operator is shorthand for Not-And.

The Xor operator–shorthand for exclusive or.

The Nor gate derives its name from Not-Or.

Any Boolean function can be realized using Nand gates only.

Truth Tables and Boolean Expressions

A turth table is often a convenient means for describing some states of nature.

The ability to simplify a Boolean expression is the first step toward hardware optimization.

1.2 Logic Gates

Computer scientist don not have to worry about physical artifacts.

Primitive and Composite Gates

Any given logic gate can be viewed from two different perspectives:

- internal
- external

1.3 Hardware Construction

1.3.1 Hardware Description Language

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