Serial_Card

A1200 Clock Port Serial Card design

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.

Why not make it a commercial product?

I have been asked to do this but considering the current state of the Amiga market, it would be hard to make a return on any outlay. I might look at producing a DIY kit.

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.

Where is the design then?

Here are the design notes, which explain how I designed this card and some decisions made.

The Schematics are here.

Some relevant timing diagrams here.

You can download everything here.

By Ian Stedman, 19th July 2002