THE MAGAZINE FOR COMPUTER APPLICATIONS
Circuit Cellar Online offers articles illustrating creative solutions
and unique applications through complete projects, practical
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The eZ80 Webserver

An 8-Bit CPU Takes on the Internet

by James Antonakos

Start ý Software Model ý Memory Map ý Instruction Set ý On-Chip Peripheral Registers ý Hardware Architecture ý TCP/IP Stack Operation ý eZ80 Evaluation Board ý Connecting the System ý Developing the Hardware and Software ý Application: A Web-Based Security System ý Other Applications ý Win Your Own! ý Sources and PDF

OTHER APPLICATIONS

I took a walk around my departmentýs floor, looking for ways to upgrade some old piece of equipment or perform some new task using the eZ80. I came up with many project ideas. For instance, a digitized voice greeting system could be developed in which a machine says, "Welcome to the electronics lab" when you open the door. Or, an online light-stick controller with a visual perception display that uses a single column of 48 LEDs with rapidly changing patterns to simulate two-dimensional pictures as the eye flicks across the column is another good idea. The eZ80 could be used in an on-line scrolling message display controller such as the one I talked about in my "An Electronic LiteShow Display" articles (Circuit Cellar Online, June and July 2001).

There are numerous other projects that could be designed. Here are some others that I thought of:

• department information server (announce tests, special events)
• on-line traffic light controller
• networked intercom modules
• networked time/date displays
• networked weather station
• networked musical chimes (would replace songs encoded on paper tape)
• online people counter (infrared beam of light across a hallway counts individuals who cross the beam)

Of course, I saved my best application for last. What I would really enjoy spending time on is a networked parallel supercomputer made of eZ80 Webservers. One eZ80 would act as the controller, with plenty of others acting as computational units that can send commands from the controller, do their calculations in parallel, and forward their results back to the controller. Ethernet switches would be used to connect all the web servers.

In order to see how the number of web servers operating in parallel affects the overall computational speed of the supercomputer, I would use a visual aid. The eZ80 Webserver computational units would be calculating their own slice of a two-dimensional Mandlebrot set (this will help get the Mathematics Department interested in the project). They would report their graphical results to the controller, which would simply turn on pixels at appropriate screen locations in a display. The larger the number of computational units, the faster the Mandlebrot image would be rendered. I may have my digital students build their own web server board and add it to the supercomputer, so the system would grow larger every year.

Anyone who wants to borrow any of these proposed applications, be my guest. Beat me to it. Get your own networked supercomputer working before I do and send me email saying "Ha, ha!" That would be exciting.