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Page last updated
20 January 2023

It's a Rodez

It's actually a Rodez V1.0 BBC User Port Switch.

Some people would refer to it as a 'Port Splitter' or 'Expansion Unit'. I add those quotes just for the search engines.

If you haven't read it already, see the previous page to learn how I came to own a BBC Micro.

I think the seller felt sorry for me, so he gave me a good price.
When I encountered the need for a User Port Switch, we agreed to name it after him.

On EBay, his seller ID is Rodez.

Bare board

Bare board    The new, unpopulated board.

You can probably see, the connector will now fit correctly.

Populated board

Populated board   
The board with all parts populated.

Two wire links beneath second chip. To prevent them flapping about I added some superglue.

Unfortunately, it spilled slightly, causing the greasy looking smear at bottom left.

I will not use that again.

Working board

Working board   
Connected and working.

I could only find white LEDs for my quick test. Turns out they were ultra bright.
Out of habit I used a resistor for 3.3v supply. This circuit is 5 volts.

I need to adjust the resistor to bring the glare down a touch.

Mounted in the left socket is my Turbo MMFS card.

The right socket will contain my Concept Keyboard. Now that I have the switch working, I can work on the Concept Keyboard code, test and save my work. Without having to disconnect, re-connect.

Don't do what I did

BBC 1   
Don't do what I did !!!.

I checked the circuit diagram over, and over.
I checked the PCB layout over and over.

If you look closely at the image, you will see that the connector will not fit.

I understood IDC type connectors were all the same size. They are not.
The one I chose from the parts list on the schematic design software, were 2mm pitch.
The IDC connector on the BBC Micro User Port is a 2.54 millimetre pitch.
The software I use automatically exports the part type over to the PCB design sheet. I never even though to check that.

This added more cost and production time because I had to redesign the board and re-order.

Gutted !!!

------------ Maddog