Actually update spec

This commit is contained in:
Lior Halphon 2021-04-12 22:43:23 +03:00
parent 9a1f962281
commit 9c1889f450
1 changed files with 16 additions and 15 deletions

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@ -73,8 +73,9 @@ For example; `'GD '` represents a DMG of an unspecified revision, `'S '` repr
The values of memory-mapped registers should be written 'as-is' to memory as if the actual ROM wrote them, with the following exceptions and note: The values of memory-mapped registers should be written 'as-is' to memory as if the actual ROM wrote them, with the following exceptions and note:
* Unused registers have Don't-Care values which should be ignored * Unused registers have Don't-Care values which should be ignored
* Unused register bits have Don't-Care values which should be ignored * Unused register bits have Don't-Care values which should be ignored
* The value of KEY0 (FF4C) must be valid as it determines CGB mode * The value of KEY0 (FF4C) must be valid as it determines DMG mode when the model is CGB or newer
* Sprite priority is derived from KEY0 (FF4C) instead of OPRI (FF6C) because OPRI can be modified after booting, but only the value of OPRI during boot ROM execution takes effect * Sprite priority is derived from KEY0 (FF4C) instead of OPRI (FF6C) because OPRI can be modified after booting, but only the value of OPRI during boot ROM execution takes effect
* If a register doesn't exist on the emulated model (For example, KEY0 (FF4C) on a DMG), its value should be ignored.
* BANK (FF50) should be 0 if the boot ROM is still mapped, and 1 otherwise, and must be valid. * BANK (FF50) should be 0 if the boot ROM is still mapped, and 1 otherwise, and must be valid.
* Implementations should not start a serial transfer when writing the value of SB * Implementations should not start a serial transfer when writing the value of SB
* Similarly, no value of NRx4 should trigger a sound pulse on save state load * Similarly, no value of NRx4 should trigger a sound pulse on save state load