Some thoughts on new keyboards. Molding new key caps is too expensive so we need an alternative. Off the shelf key caps are standardised for common PC keyboard layout. Both the A1200 and common PC keyboards use a standard pitch of 19mm (1 x 1 key). Keys vary in widths in increments of 0.25 x standard pitch. Most keys are 1 row high with exceptions like the Return and Enter keys common to both layouts. The side profile of keys varies according to which of the six rows they are in. There are usually four or five profiles for the single row keys with at least one row sharing a profile with its neighbour.
The differences between the common PC and Amiga 1200 layout are:
Top row function keys on PC keyboard are 1 x 1 size in three groups of four keys, F1 through F12. The A1200 uses 1 x 1.25 size function keys in two groups of five keys, F1 through F10. 1 x 1.25 size keys are unlikely to be available in a profile suitable for the top row. A possible solution is to use 1 x 1 keys in two groups of six. This give a total width of 6 units per group instead of 6.25. If the keys are centred in the slots at the standard pitch the extra gap at each end is only 0.125 of a key or 2.375mm. Now we have twelve function keys instead of ten but there is only room for one new key in the A1200 keyboard matrix (89 of the 96 keys are mapped in a 15 x 6 matrix and the seven modifiers are mapped directly 1 x 7). It should be possible to configure the matrix membrane for the new keys to trigger both a standard key and a modifier e.g. F11 triggers the left Amiga and F1 keys and F12 left Amiga and F2. Some diodes, resistors or simple logic gates may be needed.
The next A1200 row begins with a strange key, the`~ key, This key is 1 x 1.5 size on the A1200 but the corresponding PC key is only 1 x 1. Next on the A1200 are the numeral keys '1' through '9' and '0', followed by three symbolic keys and the Back Space key ends the main area group. All these A1200 keys a 1 x 1 giving a total width for the main area of 15.5 units. The PC has one less symbolic key in this row group but a 1 x 2 Back Space key giving a total width for the main area of 15 units. Unless this row matches the profile of the next row a 1 x 1.5 size key may not be available in the correct profile. The next group on this row for the A1200 are the Del and Help keys, these are also 1 x 1.5 size. The PC has three 1 x 1 size keys Insert, Home, Page Up. The final group belongs to the numeric keypad and this is not a problem. A possible solution is to start the A1200 row further in with a replacement 1 x 1 size key and to replace Del and Help keys with 1 x 1 keys and add a new 1 x 1 key (Ins? It could trigger both a modifier and the numeric keypad '0').
The next row begins with the TAB key on the A1200 it's 1 x 2 and on the PC it's 1 x 1.5. If the profile is the same as the previous row a PC Back Space size key could be used but if it's not and the change suggested above is implemented, for a consistent group width a PC TAB key can be used. The rest of the row is good.
The next row starts with the Ctrl key on the A1200 and Caps Lock on a PC. The PC Caps Lock is 1 x 1.75. The A1200 Caps Lock is 1 x 1 but includes an LED and has the 1 x 1.25 Ctrl key before it. If the row profile is the same as the next row a PC left Shift size key could be used if it's sized to allow an extra symbolic key next to it but if it's too big there is unlikely to be a matching PC key. If the changes suggested above have been implemented the A1200 Ctrl key could be moved to the bottom row and a choice of widths for the A1200 Caps Lock key should be possible either with an embedded LED or with one to the left of the key.
The next row starts with left Shift this is 1 x 1.75 on an A1200. A PC Caps Lock key may be the correct size if the rows have the same profiles. If the PC left Shift key cap is available in 1 x 1.25 it can be substituted to match the above changes. If however it is only available in 1 x 2.25 it's no good. Some PC keyboards are missing a symbolic key to the right of the left Shift corresponding to the blank/international key on the A1200. In a worst case scenario we may be forced to use an indented 1 x 1 key for left Shift. The rest of the row should be fine, the 1 x 2.75 right Shift key seems to be common.
The final row may have the Ctrl key moved on to it. PC Ctrl, Windows and Alt keys seem to be the same size as the remaining A1200 modifiers left Alt, left Amiga, right Amiga and right Alt, all are 1 x 1.25. The Space Bar will need to be shorter if the Ctrl key is moved to this row.
If the suggested changes to the left edge keys have been made the maximum width of the main key area will be 15 units instead of 15.5. If the keys are centred in the main keyboard area slot this will still leave a noticeable gap either side (of 0.25 * 19mm = 4.75mm). Possible solutions could be to add pieces to the case parts molds to produce filler strips in the in colours to match the keyboard to the case. The left strip may also include an LED or light pipe housing if no led is embedded in the Caps Lock key. If molding these fillers is not possible maybe suitable pieces can be laser cut or 3D printed.
Depending on what key switches/actuators/contacts are chosen a laser cut and/or 3D printed and/or milled laminated switch housing plate with spacers, membrane location points and screw holes to attach the rest of the metal work should be manufacturable at a reasonable price if you can find the right people. CBM/Mitsumi molded parts because it would save money on mass production to get the cost of the keyboard right down. For a smaller production with a higher budget per item molding parts shoudn't be needed.
