Why no ADB to Plus Keyboard converter?
I know about the Cassie Keyboard Prototype Interface Box. It is easy to understand why Apple would not have produced such a device to allow their 128k-Plus keyboards to use ADB, if for no other reason than they would want to sell the more expensive newer ADB keyboards. What I don't understand from reading various articles from the period is why no third party vendors offered such a device. After all, When Apple introduced ADB on the SE & MacII (we're talking Macs here, not Apples, so the IIgs doesn't count), they charged you extra for one of two keyboards. Not only that, but the chief complaint about the Apple Basic Keyboard and the Apple Extended Keyboard was that they were huge compared to the older non-ADB (I suppose a shrewd consumer would have special ordered a IIgs keyboard at that point which had a much smaller footprint, but still paid extra for it none-the-less). Many also preferred the feel of the older keyboard keys for typing to the new ADB designed ones. If the ADB Mac was your first Mac, I suppose buying a new keyboard was no problem. But for the many older Mac users that eventually upgraded to a new ADB Mac, I would imagine the prospect of paying extra for a new keyboard was a slap in the face, when they had a perfectly fine one they may have even preferred typing on, not to mention the size, already connected to their old Mac. A simple interface box would have certainly solved a lot of those complaints -- it could have even had an old mouse port and done double duty -- no need to buy new peripherals to use your new Mac. The closest thing to it I have found is the Data Desk Mac101E keyboard that had dip switches allowing you to switch between old and ADB Macs. If that were possible, why didn't someone produce a simple, inexpensive interface box? I may try to build the Cassie interface box as the schematics were kindly posted: http://www.applefritter.com/node/313 but it would be nice if the chip were identified. I'm sure it's just a stock IC and as long as it is appropriately connected should perform exactly the way the Cassie box does.

