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INTERACTIVE KEYBOARD
SIGNAL FLOW
[CPU 6502A] ─→ writes to ─→ [AY-3-8912 Reg 14] ─→ selects column (PA0-PA7)
[CPU 6502A] ─→ writes to ─→ [VIA PB0-PB2] ─→ [4051 MUX] ─→ selects row
[VIA PB3] ←── reads ←── key connection result (1=pressed, 0=open)
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KEYBOARD MATRIX (8×8)
| Row \ Col | PA0 | PA1 | PA2 | PA3 | PA4 | PA5 | PA6 | PA7 |
|---|---|---|---|---|---|---|---|---|
| 000 | 7 | N | 5 | V | R-Ctrl | 1 | X | 3 |
| 001 | J | T | R | F | ESC | Q | D | — |
| 010 | M | 6 | B | 4 | CTL | Z | 2 | C |
| 011 | K | 9 | ; | - | < | \ | ' | — |
| 100 | Space | , | . | ↑ | L-Shift | ← | ↓ | → |
| 101 | U | I | O | P | FCTN | DEL | ] | [ |
| 110 | Y | H | G | E | AltGr | A | S | W |
| 111 | 8 | L | 0 | / | R-Shift | Return | CAPS | = |
🔵 Column (PA) highlighted🟢 Row (PB) highlighted🟠 Key detected