A1200 Clockport serial card design concept

Current Status: Concept only, untested
Date:                  19th July 2002
License:             Creative Commons Attribution 3.0 Unported License
Design summary:
Probably a first, a complete but untested, design for the A1200 clock port.
Schematics, design notes and some timing diagrams included.

Why do this?

I have authored a technical note  on Aminet on the clock port and received a few emails asking how to design a card for the clock port. The best way to answer the emails would have been to send a design, which I did not have. So I set about designing a serial port card to  learn more. This is the result.

What about software?

This is the biggest problem. A driver would need to be written. It may work with other clock port serial cards as they are of similar design but I have not tried this.

What are the specifications?

  • Uses a PC16550D UART, the original from National Semiconductor that is used in most PCs, capable of 1.5MBaud, limited to 250KBaud in this design.
  • The UART has a 16 byte FIFO to reduce CPU overhead.
  • 250 KBPS max data rate.
  • Only requires 3 ICs.

Design files

Here are the design notes, which explain how the card was designed and some of the design decisions.

The Schematics are below:

You can download everything here.

 By Ian Stedman, 19th July 2002