Difference between revisions of "83Plus:Hooks:9BD4"
From WikiTI
84plusfreak (Talk | contribs) m (→Credits and Contributions) |
(→Using the Hook: Zero flag aborts, not B=0) |
||
| Line 19: | Line 19: | ||
** C holds the complement of these bits. | ** C holds the complement of these bits. | ||
* B always contains the constant 2Ch. | * B always contains the constant 2Ch. | ||
| − | * Return | + | * Return Zero flag to abort linking. |
== Comments == | == Comments == | ||
Revision as of 21:02, 11 June 2005
Synopsis
Name: USB Activity Hook
Hook Pointer Block Address: 9BD4
Hook Enable BCALL: 528A
Hook Disable BCALL: 528D
Hook Call BCALL: (none known)
Hook Active Flag: 0, (iy+3Ah)
This hook is called from the interrupt routine when USB activity is detected.
Using the Hook
- The hook is called whenever any of bits 4-0 of port 55h are low.
- C holds the complement of these bits.
- B always contains the constant 2Ch.
- Return Zero flag to abort linking.
Comments
This hook was introduced in OS 2.30. Apps should check the OS version before attempting to use this hook.
Credits and Contributions
- 84plusfreak (Sernin van de Krol) discovered and analyzed this hook.
