Digital Logic Tutorial

Contents

• NAND The logical basis of all computing
  • And how they can make all the other gates
  • XOR and XNOR, different or equal
• RS Flip Flop How computers learn and remember
  • although the D Flip Flop is a bit closer to a bit.
• Binary and Decimal Numbers Count like a computer
• Binary Addition Circuit NANDs can Add! A little bit anyway.
  • Binary Full Adder but NAND adders can really add.
• A 2 bit to 4 line active low decoder Stepping through a sequence.

Next

How a very simple little "gate" or elemental bit of logic is the basis of all computing.

Also:

• Bitwise operations in C/C++

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://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://elearning.cizgi.com.tr/logisim.aspx
• 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 multi-level 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.

Peter Todd has released source and sample projects for his artwork, including his 3d wireframe cube renderer for the PIC 18f6520 This includes examples of hardware developed with free software tools such as gEDA/gschem/PCB, SDCC, gputils and picp all on Linux. http://petertodd.ca/art/source-code/

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