Differences
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| documentations:devices:6821 [2015/03/01 17:53] – [Sound and Games PIA] pulkomandy | documentations:devices:6821 [2018/08/17 09:08] – [MO System PIA] pulkomandy | ||
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| ===== Uses ===== | ===== Uses ===== | ||
| ==== MO " | ==== MO " | ||
| - | === data port A === | + | === data port A (A7C0) |
| * bit 0: /FORME - Switch the screen RAM mapping between pixel and attribute RAMs | * bit 0: /FORME - Switch the screen RAM mapping between pixel and attribute RAMs | ||
| * bits 1-4: border color (R,G,B,P) | * bits 1-4: border color (R,G,B,P) | ||
| Line 52: | Line 52: | ||
| Bit 7 is low when no tape drive is plugged, and high when there is one. The monitor loading and saving code checks for this to detect the tape drive. | Bit 7 is low when no tape drive is plugged, and high when there is one. The monitor loading and saving code checks for this to detect the tape drive. | ||
| - | === data port B === | + | === data port B (A7C1) |
| * bit 0: sound output | * bit 0: sound output | ||
| * bits 1-3: keyboard column to scan | * bits 1-3: keyboard column to scan | ||
| Line 58: | Line 58: | ||
| * bit 7: state of key selected by the column and line | * bit 7: state of key selected by the column and line | ||
| - | === Control ports === | + | === Control ports (A7C2, A7C3) === |
| * CA1: lightpen interrupt (IRQA is wired to 6809 FIRQ) | * CA1: lightpen interrupt (IRQA is wired to 6809 FIRQ) | ||
| * CA2: tape drive motor control (output) | * CA2: tape drive motor control (output) | ||
