The Motorola 6845 CRTC
6845 Registers
The 6845’s register numbers are frequently given in either decimal or hexadecimal. Motorola’s own references use decimal, so that is what we will use here.
| Index | Hex | Name |
|---|---|---|
| 0 | 00h | Horizontal Total |
| 1 | 01h | Horizontal Displayed |
| 2 | 02h | Horizontal Sync Position |
| 3 | 03h | Sync Width |
| 4 | 04h | Vertical Total |
| 5 | 05h | Vertical Total Adjust |
| 6 | 06h | Vertical Displayed |
| 7 | 07h | Vertical Sync Position |
| 8 | 08h | Interlace Mode and Skew |
| 9 | 09h | Max Scan Line Address |
| 10 | 0Ah | Cursor Start |
| 11 | 0Bh | Cursor End |
| 12 | 0Ch | Start Address (High) |
| 13 | 0Dh | Start Address (Low) |
| 14 | 0Eh | Cursor Address (High) |
| 15 | 0Fh | Cursor Address (Low) |
| 16 | 10h | Light Pen Latch Address (High) |
| 17 | 11h | Light Pen Latch Address (Low) |