system_interface
Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revision | |||
| system_interface [2025/08/21 12:25] – reggie | system_interface [2025/08/26 15:57] (current) – [Keyboard] reggie | ||
|---|---|---|---|
| Line 67: | Line 67: | ||
| Columns and rows are zero-based with (0, 0) at the (left, top). Addresses increase left to right, then top to bottom, for a 32 wide and 16 high display. So column 7, row 3 is at address $400+(3*32)+(7). | Columns and rows are zero-based with (0, 0) at the (left, top). Addresses increase left to right, then top to bottom, for a 32 wide and 16 high display. So column 7, row 3 is at address $400+(3*32)+(7). | ||
| - | ==== Keyboard ==== | + | ==== Keyboard |
| The keyboard is accessed by a single port. Simply write 0 to the port then read from the same address. A negative value means no key has been pressed, otherwise the value is the ASCII code of the last key pressed. Write $ff to the same port to clear the keyboard buffer. | The keyboard is accessed by a single port. Simply write 0 to the port then read from the same address. A negative value means no key has been pressed, otherwise the value is the ASCII code of the last key pressed. Write $ff to the same port to clear the keyboard buffer. | ||
system_interface.1755779115.txt.gz · Last modified: 2025/08/21 12:25 by reggie