Difference between revisions of "OSBYTE &53"
Tom seddon (talk | contribs) (Created page with "OSBYTE &53 (83) - Retro Hardware ADJI (Advanced Digital Joystick Interface): Placeholder value for KEYV handler Not actually realistically callable via OSBYTE. The ROM can h...") |
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Not actually realistically callable via OSBYTE. | Not actually realistically callable via OSBYTE. | ||
Revision as of 23:00, 9 September 2023
OSBYTE &53 (83): Retro Hardware ADJI (Advanced Digital Joystick Interface): Placeholder value for KEYV handler
Not actually realistically callable via OSBYTE.
The ROM can hook into KEYV and BYTEV, which it does through a little routine stored at a configurable address in memory, bypassing the extended vector mechanism in order to accommodate games that overwrite that region.
To keep the routine small, it funnels both KEYV and OSBYTE calls into the same entry point in the ROM, and &53 - unused on both Master 128 and Electron - indicates that the call is being made through KEYV rather than BYTEV.
