As you probably know, the original Macintosh 128K, 512K (Fat Mac) and the Macintosh Plus (IIRC) have a different keyboard and mouse connection than the later ADB versions such as the Macintosh SE series.

The keyboard looks to use an RJ-11 jack and the mouse used a 9 pin serial connector. Many times finding a replacement keyboard and mouse for those models can cost more than the Mac itself.

So my question is, was there an official (or third party) adapter to convert more common ADB keyboards to work with those models of Macintosh? I suspect that it's more difficult than a straight pin converter. I also suspect those keyboards and mice used a different serial protocol than ADB.

Any information on this would be appreciated.


  • I've never seen an adapter. The original Macintosh keyboard even had an oddball cable. The ends were the same as a telephone handset cord, but different polarity: you could burn up your keyboard if you substituted a handset cord for the original.
    – Whit3rd
    Sep 17, 2017 at 3:47
  • 1
    That telephone cord typically used an RJ-11 jack (en.wikipedia.org/wiki/Registered_jack). The neat thing about RJ-11's are they only had four wires and are easier to create than DIN's. No soldering required.
    – cbmeeks
    Sep 18, 2017 at 12:25

2 Answers 2


With enough work, anything can be adapted. However, I’m unaware of any products that will implement an ADB host controller and act as an original Macintosh keyboard and mouse. Any such product will probably be comparable in price to just obtaining the correct keyboard and mouse for the Macintosh.

As you guessed, the protocols are very different, the original keyboard spoke a simple TTL-level serial protocol, the original mouse provided quadrature signals the computer had to interpret, and ADB is more like a network.

Also, just FYI, the Macintosh mouse did not use a “9-pin serial connector,” both PC/AT serial and the original Macintosh mouse used DE-9 connectors.

  • 1
    I knew it was a 9 pin something. :-)
    – cbmeeks
    Sep 18, 2017 at 12:27

The closest thing I have seen is bbraun's adapter which allows you to connect a PS/2 keyboard and mouse. You can't buy one as far as I am aware, though I believe he provides all the PCB design files and source code for you to make your own.

  • Then there's the Wombat which will convert ADB<->USB, but I don't think it talks PS/2 on the USB port so a passive USB to PS/2 adapter may not work. Sep 17, 2017 at 5:18
  • 1
    Ok here's the missing link: an active USB-female to PS/2 male adapter: kvm-online.de/index.php?cat=WG230&product=KMU2P Sep 17, 2017 at 5:29
  • 1
    With so many unpowered adapters hooked inline, you may need supplemental power to avoid frying your Mac's keyboard and mouse ports.. Sep 17, 2017 at 5:40
  • 1
    I'm not sure if cbmeeks needs ADB peripherals specifically, or just asked about that because it seemed to them the most likely thing to exist. Sep 17, 2017 at 5:44
  • 1
    @scott.squires my main reason for asking the question is that I see "pre-SE" Macs on eBay all the time but they almost never come with a keyboard or mouse. Or, the seller sells them separately because he knows how rare they are. Which is frustrating. I'd love to have a 512K Mac and I don't want to use PS/2. At least a small ADB would be "somewhat" accurate. :-)
    – cbmeeks
    Sep 18, 2017 at 12:28

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .