Memory Map
| Use | Start - End | Implementation |
|---|---|---|
| RAM | 0000 - DFFF | 56K NVRAM |
| D000 - D0FF | ASSIST09 working RAM, stacks and vector copies | |
| I/O | E000 - E3FF | Main Bus Select 0 1K |
| E400 - E7FF | Main Bus Select 1 1K | |
| E800 - EAFF | unassigned | |
| EB00 - EBFF | ACIA Select 256b | |
| EC00 - EEFF | unassigned | |
| EF00 - EFFF | Memory Latch Select 256b | |
| ROM | F000 - FFFF | EEPROM 4K |
| F000 - F3FF | ASSIST09 Expansion ROM area (unused) | |
| F800 - FFFF | ASSIST09 | |
| MPU | FFF0 - FFF1 | HD6390 Illegal Opcode/Divide By Zero Trap vector (FFD4) |
| FFF2 - FFF3 | SWI3 vector (FFD8) | |
| FFF4 - FFF5 | SWI2 vector (FFDC) | |
| FFF6 - FFF7 | /FIRQ vector (FFE0) | |
| FFF8 - FFF9 | /IRQ vector (FFE4) | |
| FFFA - FFFB | SWI vector (FFE8) | |
| FFFC - FFFD | /NMI vector (FFEC) | |
| FFFE - FFFF | /RESET vector (F837) |
The 2.0 board is hard wired for “Exxx” selects in the map above.
The subsequent version has jumpers to locate the I/O block
These use J3 select jumper for 8xxx - Exxx address select range
Return to SST-6809