Jeff wrote: ↑
Mon Mar 09, 2020 6:28 pm
I was comparing key layouts between OSI and Apple II, and noticed that the Apple Right Arrow is in the same position as the OSI Shift Lock. Am I correct to assume that I should just install a normal switch in that location?
Yes, just install a normal key. The Apple2 keymap will map it to an arrow key, and the "classic" keymap will map it to a RUBOUT key.
And what about the diode for that key? It seems that there is not a place for one.
The keyboard is designed to work with a direct OSI-compatible interface as well as an ASCII interface. The row-column organization of the keys is therefore OSI compatible, in which the BREAK key is connected to a RESET circuit, and (in my OSI interface) the SHIFTLOCK will optionally be connected to a soft-latch circuit to be able to use regular key switches and also drive an LED indicator.
Since these keys are special in the OSI interface, no diodes are include on the keyboard, and the keys are not wired into the matrix, but instead, both connections for each switch are brought directly to the interface board. The ASCII interface doesn't treat the keys as special, and simply wires those keys back into the matrix, with the diodes. So the ASCII interface sees those keys in the matrix.
On the interface board, please confirm that R1 and R5 are 330 ohms and D3 and D12 are 1N4148's.
Yes, but you could increase the value if you find the LEDs too bright. For the diodes, 1N4148 or 1N914 parts will work fine. Make sure you double-check that all the diodes are oriented correctly before you solder in the keys. The diodes will be hard to change once the whole keyboard is installed. Although you could install the diodes on the back. Then replacing them would not be too hard.