Table 9-1. Apple ][+ I/O Unit addresses
| Addr | Name | Access | Description | Unit |
|---|---|---|---|---|
| C000 | KBD | R | Last key pressed | Keyboard |
| C010 | KBDSTRB | RW | Keyboard Strobe | Keyboard |
| C020 | TAPEOUT | R7 | Toggle Cassette Tape Output | |
| C030 | SPKR | R | Toggle Speaker | Speaker |
| C040 | STROBE | R | Game I/O Strobe Output | Game |
| C050 | TXTCLR | WR | Display Graphics | GraphicMode |
| C051 | TXTSET | WR | Display Text | GraphicMode |
| C052 | MIXCLR | WR | Display Full Screen | GraphicMode |
| C053 | MIXSET | WR | Display Split Screen | GraphicMode |
| C054 | TXTPAGE1 | WR | Display Page 1 | GraphicMode |
| C055 | TXTPAGE2 | WR | Display Page 2 | GraphicMode |
| C056 | LORES | WR | Display LoRes Graphics | GraphicMode |
| C057 | HIRES | WR | Display HiRes Graphics | GraphicMode |
| C058 | CLRAN0 | WR | Annunciator 0 Off | Game |
| C059 | SETAN0 | WR | Annunciator 0 On | Game |
| C05A | CLRAN1 | WR | Annunciator 1 Off | Game |
| C05B | SETAN1 | WR | Annunciator 1 On | Game |
| C05C | CLRAN2 | WR | Annunciator 2 Off | Game |
| C05D | SETAN2 | WR | Annunciator 2 On | Game |
| C05E | CLRAN3 | WR | Annunciator 3 Off | Game |
| C05F | SETAN3 | WR | Annunciator 3 On | Game |
| C060 | TAPEIN | R7 | Read Cassette Input | |
| C061 | PB0 | R7 | Switch Input 0 | Game |
| C062 | PB1 | R7 | Switch Input 1 | Game |
| C063 | PB2 | R7 | Switch Input 2 | Game |
| C064 | PADDL0 | R7 | Analog Input 0 | Game |
| C065 | PADDL1 | R7 | Analog Input 1 | Game |
| C066 | PADDL2 | R7 | Analog Input 2 | Game |
| C067 | PADDL3 | R7 | Analog Input 3 | Game |
| C070 | PTRIG | R | Analog Input Reset | Game |
| C080 | R | Read RAM bank 2; no write | LanguageCard | |
| C081 | RR | Read ROM; write RAM bank 2 | LanguageCard | |
| C082 | R | Read ROM; no write | LanguageCard | |
| C083 | RR | Read/write RAM bank 2 | LanguageCard | |
| C084-C087 | Same as C080-C083 | LanguageCard | ||
| C088 | R | Read RAM bank 1; no write | LanguageCard | |
| C089 | RR | Read ROM; write RAM bank 1 | LanguageCard | |
| C08A | R | Read ROM; no write | LanguageCard | |
| C08B | RR | Read/write RAM bank 1 | LanguageCard | |
| C08C-C08F | R | Same as C088-C08B | LanguageCard | |
| C090-C09F | Slot 1 addresses | Slots | ||
| C0A0-C0AF | Slot 2 addresses | Slots | ||
| C0B0-C0BF | Slot 3 addresses | Slots | ||
| C0C0-C0CF | Slot 4 addresses | Slots | ||
| C0D0-C0DF | Slot 5 addresses | Slots | ||
| C0E0-C0EF | Slot 6 addresses | Slots | ||
| C0F0-C0FF | Slot 7 addresses | Slots |
R - Read to act or get information, W - Write to act, RR - Read twice to act, R7 - Read information from bit 7