ASCII-EX mapper
From MSX Game Library
Here's a proposal for a mapper format operating with a 16-bit segment register and allowing ROMs of 512 MB (8 KB segment) or 1 GB (16 KB segment).
The idea is to use the ASCII8/16 mapper format as a basis and extend it using memory space unused by the original design (here we use the 8000h~9FFFh range).
MRC16 mapper
| Bank (16kB) | Switching address | Initial segment |
|---|---|---|
| 4000h~7FFFh (mirror: C000h~FFFFh) | Lower byte: 6000h (mirrors: 6001h~67FFh) Higher byte: 8000h (mirror: 8001h~87FFh) |
0 |
| 8000h~BFFFh (mirror: 0000h~3FFFh) | Lower byte: 7000h (mirrors: 7001h~77FFh) Higher byte: 9000h (mirror: 9001h~97FFh) |
0 |
MRC8 mapper
| Bank (8kB) | Switching address | Initial segment |
|---|---|---|
| 4000h~5FFFh (mirror: C000h~DFFFh) | Lower byte: 6000h (mirrors: 6001h~67FFh) Higher byte: 8000h (mirror: 8001h~87FFh) |
0 |
| 6000h~7FFFh (mirror: E000h~FFFFh) | Lower byte: 6800h (mirrors: 6801h~6FFFh) Higher byte: 8800h (mirror: 8801h~8FFFh) |
0 |
| 8000h~9FFFh (mirror: 0000h~1FFFh) | Lower byte: 7000h (mirrors: 7001h~77FFh) Higher byte: 9000h (mirror: 9001h~97FFh) |
0 |
| A000h~BFFFh (mirror: 2000h~3FFFh) | Lower byte: 7800h (mirrors: 7801h~7FFFh) Higher byte: 9800h (mirror: 9801h~9FFFh) |
0 |