By the way, in 1977 I made and sold a SOL-20 keyboard modification kit that included a new ROM for the keyboard and new keytops. The new ROM made the high order bit of the numeric keypad keys a "1" instead of a "0". This made it possible to distinguish between the keys in the numeric keypad and the numeric keys in the top row of the normal keyboard (in the stock keyboard, these different keys produced exactly the same output). This was transparent to normal applications because they normally did an "ANI 7FH" anyway, stripping this bit, but it could be used by an application if the application wanted to do so.

The new keytops had word processing legends instead of numbers, and really was made for the "Electric Pencil" and "Wordstar" word processors. The keytops were actually made by Keytronic (I had to pay tooling charges, about $1,000 (those were 1977 dollars, it was about one-fourth the price of a new car)) and and matched the SOL keyboard exactly. I have a few of these kits left in a box in the basement. If anyone wants them, they are $25. What I'm not sure of is if I have the installation instructions anywhere. [If anyone takes me up on this, I'm actually going to have to FIND that box, which may be easier said than done.]