Z80 Circuit and Controller Project

12/11/2001

There are a series of short breadboard labs for the Z80 microprocessor that are worthwhile. The schematics are available as pdf files for printout, and there are a series of construction details and test procedures as well.

Z80 Breadboard Construction Labs

These Z80 Labs start with as few as 3 to 5 chips, and allow observation of very basic CPU activity. Clock cycles for the Z80 can be extremely slow, and thereby can be used to a distinct advantage in comprehending what is and should be happening during memory cycle fetch and decode, and I/O activity requests.

• This Z80 Circuit and Controller Project allows the individual to build an actual working 8-Bit Computer/Controller, with Indicators for Address-Lines, Data-Lines, CPU Status-Indication, and I/O-Lines.
• For those folks who would like to breadboard this circuit, a full schematic (511Kb pdf) is available here.
• A professional quality 2-sided circuit board (8.25"x10.5", 534Kb pdf) is available at my cost to individuals or schools. I had originally designed these boards for student's use, so that they would not have to take the extensive time it takes to breadboard them in the classroom. It saved a little over 1 week of 6hr classroom days in construction and testing. Populated (438Kb pdf) it looks like this. (These take about 3 min each to download at 28.8Kb)
• The physical layout of the logic components of this good sized circuit board is in two descriptive parts, where the first describes the blocks (109Kb pdf) which overlay the actual location of the parts (150Kb pdf).
• A semi-detailed Sugested Parts List is available, with possible sources and approximate prices.
• The user will need to provide their own parts, allowing minimal construction and costs. The cost of the board, with shipping is $50.00, and includes all schematics, parts-list, and detailed instructions (1647Kb pdf). This is the cost of the boards to me, and I'm not interested in making any profit on them. If there was a great demand for them, then my purchase costs would be lower, and I could pass that on to all. (It takes about 10 min to download this pdf file at 28.8Kb)
• A suggested Check List for use during assembly is available.

Z80 Project Purpose

• The capability of this overall project allows an individual to observe and identify every single control and data signal of this computer system. This project is designed to allow super-slow clocking signals (from 5Hz down to 0.5Hz ) which allows a person to see and understand instruction fetch from memory with appropriate other memory read-write operations, and observe the activity of Data Input/Output. Clocking can be achieved at well over 100KHz, and students have reported successful clocking at over 500KHz.
• Although this circuit board was designed for teaching, it can be an actual useful circuit for robotic control, model trains, instrumentation, house management, burglar alarms, etc.
• A number of these have been constructed by students in the classroom, and they have all had favorable comments for all aspects of the finished product. It should be emphasized that experienced soldering capability is a must! There are a series of checkpoints available for the individual to determine successful construction.