Serial card

 A1200 Clock Port Serial Card design

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 here.

You can download everything here.

 By Ian Stedman, 19th July 2002

Updated 14 April 2021