Keyboard
From SpecNext official Wiki
| Number | $**FE |
|---|---|
| Decimal | 254 |
| Short desc. | Series of specific ports that read keyboard key presses. |
| Bit Mask | %xxxx xxxx ---- ---0 where only one bit in x is 0 |
| Readable | Yes |
| Writable | No |
| Subsystem | Input |
bit 6 = EAR in from the tape audio jack bits 4:0 = key column result from keyboard, active low
- nextreg 0x08 bit 0 can be set to select issue 2 keyboard which will affect reads of bit 6
Reads keys on the keyboard depending on the upper byte of the port number. The five keys are represented by bits 0-4 of the read byte, listed below with bit 4 first down to bit 0. A zero means that the key is pressed.
The top eight bits of the port address are active low signals that select one or more key rows for reading.
| Port upper byte | Keys affected (row of keys) |
|---|---|
| $7F (bit 7) | B, N, M, Symbol Shift, Space |
| $BF (bit 6) | H, J, K, L, Enter |
| $DF (bit 5) | Y, U, I, O P |
| $EF (bit 4) | 6, 7, 8, 9, 0 |
| $F7 (bit 3) | 5, 4, 3, 2, 1 |
| $FB (bit 2) | T, R, E, W, Q |
| $FD (bit 1) | G, F, D, S, A |
| $FE (bit 0) | V, C, X, Z, Caps Shift |
Wireless Keyboards
Most ps/2 keyboards commonly seen today are wired. Two models of wireless keyboard known to work well with the Next are the Microsoft Wireless Elite Keyboard 1011 and the Logitech Cordless Desktop Keyboard EX110.