XoomFloppy Pro – May it be a little more?


You get a new drive, or expand your existing drive and suddenly you are missing the parallel floppy speeder port or the IEEE-488 port.

Now of course I could have used the ZoomFloppy again, which I also have. But what always bothered me personally was the immense size of this board.

So I have to get an “extended” XoomFloppy. And so the XoomFloppy Pro was born.


The circuit diagram did not need to be changed much at all. Only the “new” connections came back. I say back because they were included in the original documents. I had omitted them for the first XoomFloppy model.

So creating a “new” schematic was quite easy:

Schematic XoomFloppy Pro

IEEE-488 Connector

For the IEEE-488 (GPIB) interface I had to decide in which version it should be mounted on the board. The de facto standard would actually be this one:

And then there is the PCB edge connector, as was common with the PET and CBM devices:

The first connection has the advantage that you can secure the connector with a screw connection. But the whole construction is very large and heavy. Also, the cables for these connectors are usually very inflexible and thick.
The platinum connector, which is similar in shape and number of pins to the userport connector on the C64, uses a very narrow connector. And the cable is usually very flexible and much thinner.

And this cable was included with every Commodore IEEE-488 drive at that time, because as already mentioned, the Commodore computers use just this connector. Also this cable can be found on eBay from time to time much cheaper than the standard IEEE-488 connection cable.

So it was quite easy for me to choose the board edge connector. Especially since here even costs for the quite expensive IEEE-488 connector can be saved, since only the appropriate contacts on the board must be provided.

XoomFloppy Pro

And that’s how the XoomFloppy Pro was “born”…

The equipment is as follows:

  • Serial CBM bus (IEC) as DIN socket
  • Parallel floppy speeder connector as
    • board edge connector (“user port” connector)
    • D-SUB15 connector
  • IEEE-488 (GPIB) connector
    • Board edge connector (PET/CBM variant)
    • Pin header for ribbon cable
  • Activity LED
  • MicroUSB

It was not possible to make it much smaller, because the two board edge connectors determine the width of the board, and the D-SUB15 connector is also quite wide. But the latter is very popular and quite widespread.

What was still missing now, which was a…


Such a case is a practical thing after all. For one thing, the circuit board is better protected, and it also simply looks better.

So I have also designed a small housing, in which the board fits perfectly.

Das Gehäuse besteht auch zwei Hälften und wird einfach nur ineinander gesteckt. Es muss also nichts geschraubt oder geklebt werden. Das Gehäuse kann man so leicht auf einem 3D Drucker herstellen.

Oben gibt es eine Aussparung für eine LED. Ich habe eine LED genommen, die oben abgeflacht ist. So kann diese bündig mit dem Gehäuse abschließen.

Am einfachsten ist es, die LED erst in das Gehäuse zu stecken, die Platine drüber zu legen und dann erst fest zu löten. So passt das ganze sehr präzise zusammen und man hat weniger fummelei.


All information, files and the case can be found on my GitHub: https://github.com/DL2DW/XoomFloppy_Pro_2018

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