Keymap High Address Register
From SpecNext official Wiki
| Number | $28 |
|---|---|
| Readable | Yes |
| Writable | Yes |
| Short Description | High address of Keymap (MSB in bit 0), read palette half-value from $44 |
Write:
bits 7:1 = Reserved, must be 0 bit 0 = MSB keymap address
Read:
bits 7:0 = Stored palette value from Enhanced ULA Palette Extension ($44)
This value does update right after writing first 8 bits of colour to NextReg $44, while the palette entry is modified only after the second write (adding ninth bit and L2 priority bit) is done. So half-written value can't be read back through Palette Value Register ($41), but can be read with this register.