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Rev 4
New Rev 4 Board
A newer version (Rev 4) of this circuit board is available. Rev 4 includes a faster CPU, more memory, more I/O and an optional LCD. We recommend you use Rev 4 for new projects. We are keeping these very old pages on-line for reference to assist people who build the original version of the 8051 development board.
The very old design is difficult to troubleshoot due to the use of an external 27C64 EPROM for the monitor program. We highly recommend you use the new design for any new projects.

What You Will Need

One of the most difficult parts of a hobbiest electronics project can be acquiring all of the required components. Here is a detailed parts list with some hints about where you may find the components.

There are a number of ways to construct the circuit, but wire wrap and printed circuit board construction are the two discussed here. If you're very good at soldering, a soldered point-to-point construction on the pad-per-hole 'perf board is also an option, but breadboard construction (plugging the wires into the little holes) is not reccomended for this project. Whatever construction method is chosen, taking some extra time and effort to do a neat and sturdy construction job will likely save hours of frustration while you are using the board and attempting to debug your code. Conversely, minutes saved by skipping some simple step to make your inter-connections more reliable can turn into hours trying to figure out if your code crashes due to a bug or a loose wire!

For wire wrap construction, you obviously need the wire wrap tool, wire wrap sockets, #30 solid wire, and perf board. The labels that go on the bottom side of the board are also a good idea. If you make your own labels to save money, double check them carefully, since it's easy to get the pins reversed when you flip the board over... which is the reason for having the labels on the underside of the board.

For printed circuit board construction, you obviously need to have access for a pc board fab. A double sided board is required, but the layout provided below only makes connections to the chips from the bottom side of the board, so plated-through holes are not required... assuming you solder wires into all of the via holes. Of course, you'll need the usual pc board tools: soldering iron, wire clippers, etc.

A five volt power supply is required. To use the board, a computer running an ordinary terminal program is needed. An assembler, such as AS31, is required. The EPROM on the board must be programmed with a monitor, such as PAULMON, so an EPROM programmer is needed, but only once (unless you damage the EPROM, so if you don't have ready access to a programmer, it's a very good idea to program a spare).

Testing the board requires at least a voltmeter. With luck it will work on the first try. Since the design presented here is known to work, meticulous effort and attention to detail are required to construct the board with few or no errors and to find and fix any errors. Some hints will be presented below to help you isolate problems using only a voltmeter, but ultimately most errors can only be found and fixed with careful visual inspection of your work. Detailed knowledge of the hardware's operation is of little value for troubleshooting without very fancy test equipment that is probably more trouble than it's worth. There really is no substitute for meticulous effort and attention to detail. If you do invest the time and effort to build this board, please do a high quality construction job to maximize your chances for success.

Perhaps other things are needed too that I've forgotten to mention here. If so, please let me know.

Go on to the detailed description
Skip that and go right to the schematic

Paul's Sample 8051 Development Board Design
Last updated: February 24, 2005
Statue: about 80% done now... need some photos... and proofreading
Suggestions, comments, criticisms, things you want?? <>