Difference between revisions of "Tile Definitions Base Address Register"
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:bits 5-0 = MSB of address of the tile definitions in Bank 5 | :bits 5-0 = MSB of address of the tile definitions in Bank 5 | ||
| − | The value written is an offset into Bank 5 allowing tile definitions to be placed at any multiple of 256 bytes. | + | The value written is an offset into Bank 5 allowing [[Tilemap|tile definitions]] to be placed at any multiple of 256 bytes. |
Writing a physical MSB address as $40-$7F or $C0-$FF range is permitted (the top bits will be ignored). | Writing a physical MSB address as $40-$7F or $C0-$FF range is permitted (the top bits will be ignored). | ||
The value read back may be treated as a full 8-bit value (with the top two bits equal to zero), i.e. upon writing value $EB the read of this register will produce value $2B (contrary to "reserved" bits in other registers, where read-value should be not assumed by code using it and masking by AND is recommended). | The value read back may be treated as a full 8-bit value (with the top two bits equal to zero), i.e. upon writing value $EB the read of this register will produce value $2B (contrary to "reserved" bits in other registers, where read-value should be not assumed by code using it and masking by AND is recommended). | ||
Revision as of 05:51, 23 May 2019
| Number | $6F |
|---|---|
| Readable | Yes |
| Writable | Yes |
| Short Description | Base address of the tiles' graphics. |
- bits 7-6 = Read back as zero, write values ignored
- bits 5-0 = MSB of address of the tile definitions in Bank 5
The value written is an offset into Bank 5 allowing tile definitions to be placed at any multiple of 256 bytes.
Writing a physical MSB address as $40-$7F or $C0-$FF range is permitted (the top bits will be ignored).
The value read back may be treated as a full 8-bit value (with the top two bits equal to zero), i.e. upon writing value $EB the read of this register will produce value $2B (contrary to "reserved" bits in other registers, where read-value should be not assumed by code using it and masking by AND is recommended).