Keyboard: Difference between revisions
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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. | 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. | |||
{| class="wikitable" | {| class="wikitable" | ||
! Port upper byte !! Keys affected | ! Port upper byte !! Keys affected (row of keys) | ||
|- | |- | ||
| $7F || B, N, M, Symbol Shift, Space | | $7F (bit 7) || B, N, M, Symbol Shift, Space | ||
|- | |- | ||
| $BF || H, J, K, L, Enter | | $BF (bit 6) || H, J, K, L, Enter | ||
|- | |- | ||
| $DF || Y, U, I, O P | | $DF (bit 5) || Y, U, I, O P | ||
|- | |- | ||
| $EF || 6, 7, 8, 9, 0 | | $EF (bit 4) || 6, 7, 8, 9, 0 | ||
|- | |- | ||
| $F7 || 5, 4, 3, 2, 1 | | $F7 (bit 3) || 5, 4, 3, 2, 1 | ||
|- | |- | ||
| $FB || T, R, E, W, Q | | $FB (bit 2) || T, R, E, W, Q | ||
|- | |- | ||
| $FD || G, F, D, S, A | | $FD (bit 1) || G, F, D, S, A | ||
|- | |- | ||
| $FE || V, C, X, Z, Caps Shift | | $FE (bit 0) || V, C, X, Z, Caps Shift | ||
|} | |} | ||
[[File:Speckeys.png]] | [[File:Speckeys.png]] | ||
Revision as of 08:27, 31 December 2019
| Number | PortNumber::$**FE |
|---|---|
| Decimal | NumberDec:: |
| Short desc. | ShortDesc::Series of specific ports that read keyboard key presses. |
| Bit Mask | PortMask::%xxxx xxxx ---- ---0 where only one bit in x is 0 |
| Readable | Readable::Yes |
| Writable | Writable::No |
| Subsystem | Subsystem::Input |
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 |
