Im I/O-Bereich sind acht 4er Gruppen vordekodiert.
| I/O-Belegung | |||
|---|---|---|---|
| 0x0FF 0x020 |
224 | frei | frei |
| 0x01F 0x01C |
4 | IOSEL7 | Bank-Umschalter Grundplatine/DRAM |
| 0x01B 0x018 |
4 | IOSEL6 | frei |
| 0x017 0x014 |
4 | IOSEL5 | frei |
| 0x013 0x010 |
4 | IOSEL4 | frei |
| 0x00F 0x00C |
4 | IOSEL3 | frei |
| 0x00B 0x008 |
4 | IOSEL2 | frei |
| 0x007 | 4 | IOSEL1 | PIO, Control B |
| 0x006 | PIO, Control A | ||
| 0x005 | PIO, Daten B | ||
| 0x004 | PIO, Daten A | ||
| 0x003 | 4 | IOSEL0 | CTC, Kanal 3 |
| 0x002 | CTC, Kanal 2 | ||
| 0x001 | CTC, Kanal 1 | ||
| 0x000 | CTC, Kanal 0 | ||
| Bankumschalter | |
|---|---|
| 0x0000 bis 0x1FFF | |
| RESET | ROM, BWS und SRAM |
| Bit 0 = 0 | ROM, BWS und SRAM |
| Bit 0 = 1 | DRAM |
| PIO-Anschlüsse | |||
|---|---|---|---|
| Kanal A | Kanal B | ||
| PASTB | Masse | PBSTB | frei |
| PARDY | frei | PBRDY | frei |
| PA7 | Tastatur, TAST | PB7 | Kassetteninterface, Eingang |
| PA6 | Tastatur, TD6 | PB6 | Kassetteninterface, Ausgang |
| PA5 | Tastatur, TD5 | PB5 | frei |
| PA4 | Tastatur, TD4 | PB4 | frei |
| PA3 | Tastatur, TD3 | PB3 | RTTY, PTT |
| PA2 | Tastatur, TD2 | PB2 | RTTY, Sender |
| PA1 | Tastatur, TD1 | PB1 | RTTY, Empfänger |
| PA0 | Tastatur, TD0 | PB0 | frei |
| CTC-Anschlüsse | |
|---|---|
| CLK3 | frei |
| ZC/T2 | frei |
| CLK2 | frei |
| ZC/T1 | frei |
| CLK1 | Brücke bei RTTY |
| ZC/T0 | |
| CLK0 | frei |