The logic power of computers and even microcontrollers today is mind boggling,
but even more amazing to me is that all of the functions (every one)
of the biggest computer can be shown in terms of one simple logic gate:
The NAND. Every part even Memory: From
the BIT to the Giga Byte, Math: From the most basic
Addition to the most complex Floating Point calculation,
Decision making: If not real reasoning, Input and Output
are all built from this one tiny and very simple atomic unit of logic!
In these pages my son Remy and I will start to show you how computers actually
work and how simple (and complex) they really are.
Contents
How a very simple little "gate" or elemental bit of
logic is the basis of all computing. It's just Not this AND that.
Also:
This series makes use of a program written by Andreas Tetzl of
tetzl.de that makes the NAND gate, and
the things we build from it, come alive on your screen. It is called
LogicSim and it is a digital logic
simulator that can work from a web
page. If we did not have LogicSim, we could only tell you how it all works
and could not show you. To use LogicSim, you must have
Java^{tm} from Sun Micro systems. You can check if you have
Java on their web page at
java.com. Look for the "Do
I have Java?" link.
See also:

http://www.ostracodfiles.com/basic/menu.html
An 8 bit TTL computer made from only 10 chips and an EEPROM. There are two registers (A and B) and a PC. Amazingly enough, it can do useful work with only 2 instructions: MNZ will copy data from source to destination only if A register is not zero. ADD will add source and A register then store the result in destination.+

http://www.bigmessowires.com/category/nibbler/ A 4 bit
computer design entirely from 7400 series logic
chips.+

http://dl.dropbox.com/u/1252290/Tic%20Tac%20toe.pdf TicTacToe
game made from logic circuits.+

http://www.nand2tetris.org/ "The site contains all the
software tools and project materials necessary to build a generalpurpose
computer system from the ground up. We also provide a set of lectures designed
to support a typical course on the subject."+

http://yggit.tripod.com/index.html A 4 bit computer from
discrete logic and an old ALU chip.+

http://tamswww.informatik.unihamburg.de/applets/hades/webdemos/index.html
Another java based logic simulator.+

http://www.instructables.com/id/HowtoBuildan8BitComputer/?ALLSTEPS
How to build a complete working 8 bit computer from basic logic and memory
chips. Not for the faint of heart, especially if you use a whiteboard as
does the author.+

http://www.saccade.com/writing/projects/CS428/WireWrap.html
Really nice page about a college project to build a calculator and then a
computer from TTL logic chips. This is back when people actually understood
how computers work ,o)+

http://ozark.hendrix.edu/~burch/logisim/
LogiSim (not LogicSim) is another very powerful logic simulator commonly
used for instructional purposes. It is somewhat less graphically appealing
than LogicSim.

http://ozark.hendrix.edu/~burch/socs/hymn/

http://www.sontrak.com Logic Friday
is a freeware tool for students, hobbyists, and engineers which allows them
to:

Enter a logic function as large as 16in x 16 outas a truth table, an equation,
or a gate diagram

Minimize a function quickly or exactly, compare functions, and generate new
functions as logical combinations of others

Automatically generate a multilevel minimized gate diagram using gates chosen
from a library

View any function as a truth table, equation, or gate diagram and trace the
state of each gate's outputs for a given input

Generate efficient, compact C code lookup functions from logic functions

Save functions and gate diagram images to files, export and import truth
tables as CSV files.
file: /Techref/logic/tutorial.htm, 7KB, , updated: 2013/11/15 12:17, local time: 2014/4/19 19:04,

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