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Video Tutorials

Video Tutorial 1: Overview of the Fetch operation of a fully functional simple digital computer, the "SIMCO".

Video Tutorial 2 (first half): Tracing the operation of the "simco" digital computer, logic gate by logic gate, as it follows a computer program to sound an alarm when a window is open.

Video Tutorial 2 (second half): Tracing the operation of the "simco" digital computer, logic gate by logic gate, as it follows a computer program to sound an alarm when a window is open.

Video Tutorial 2 (End of Part 2): Tracing the operation of the "simco" digital computer, logic gate by logic gate, as it follows a computer program to sound an alarm when a window is open.

Articles
Programming the SIMCO in Assembly Language

What Is A Computer? Computer Programming, The Purpose of All Computers

Building Simple Machines That Make Decisions

Getting Started Using Programmable Logic Devices


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How to build a simple digital computer - Getting Started

1. Learn Digital Logic
Computers are made up of smaller machines called logic gates. Two or more logic gates connected together comprise a digital logic circuit, and digital logic consists of the rules governing the behavior of individual logic gates and logic gates connected together to form circuits.

If you do not understand how digital logic and logic gates work, you will not be able to understand how a digital computer works, either.

The good news is that all digital logic circuits are made up of only a handful of logic gates, and the operation of the gates are very simple to understand.
Below are links to online tutorials and books on learning the basics:

PlayHookey.com Good introduction to digital logic

2. Order the laminated map of the Simple Digital Computer("SIMCO") digital logic circuit


3. Read the Gettting Started with Programmable Logic Devices tutorial by Al Williams
A programmable logic device(PLD) allows you to build actual, working digital logic circuits. The XC2C256 Cool Runner 2 PLD from XILINX is used to build the simple digital computer on this website.

To follow along in the Getting Started with Programmable Logic Devices tutorial, you will need to purchase a CPLD(Complex Programmable Logic Device) Design Kit from XILINX.
This kit contains everything you need to build the both the digital logic circuit described in the tutorial and the Simple Digital Computer you made a schematic diagram of in step 2.

4. Use the forthcoming PLD source code for the SIMCO, available from SimpleDigitalComputer.com, or create your own PLD source code.

Using the instructions for programming a CPLD from step 3, program the xilinx XC2C256 with the source code.

Presto, you've just built a working computer.

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