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.