Pitfalls with an Apple IIc to PC Com Cable

If you wish to read or write floppies between your Apple IIc and your PC, you will need a Din5 to USB/DE-9 adapter. The proper instructions for this are located here, along with purchase links:

IIc, Laser 128, and Franklin Ace 500 modem port (DIN5) cabling

But if you’re like me and don’t wish to spend 30+ dollars on a cable and USB adapter, then you can make your own! (But you’ll still need an USB adapter, maybe!)

Photograph of the outside of the adapter.
Showing two cable ends coming out of a Tupperware container.

The process is fairly simple as long as you follow the instructions provided by ADTPro. One road block I came across was the proper order of the pins on the cabling. ADTPro shows the pin numbering for the DIN5 but not the DE-9. I used a female DE-9 but while wiring it I plugged the female side to a male to male cable to make sure I didn’t screw up the ordering. I used a multimeter set to check continuity throughout to check pins and wiring. I recommend using a female adapter as most normal de-9 cables and the port on the back of your PC would be male. (Warning, I nearly cut up a NeXT cable until I noticed what it was. I don’t know how I acquired it, but don’t cut up museum pieces!) The proper ordering for the DE-9 port is shown in the following graphic:

Pinout chart for RS-232 DE-9
To protect the wire splicing, I used a Tupperware container with a hole built into one side to let the cable through. I used zip ties to hold the cable from moving. I used wire splice connectors to physically connect the two cables. I find these connectors are much simpler to work with and very strong. I used two different types in the image because I thought I may have had an interference issue, but it turns out it was the speed of the USB adapter I used.

Photo of the inside of the adapter.
Showing connector splices inside of a Tupperware container.

The adapter I purchased that seems of fairly decent quality was this one:

USB TO RS232 SERIAL DB 9 PIN COM Port Converter cable from besteworld

This adapter requires that you use a female DE-9 port. You should not need the driver CD. You will need to adjust the driver properties on Windows under “Device Manager” > “Ports” > “USB-Serial CH340”

Screenshot of baud settings in Windows.

Device Settings for USB Adapter

I set mine to use the maximum speed shown and then I no longer received any errors during transfers.

Shoot me an email if you have any trouble!

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