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 with B=0 to abort linking, similar to the silent link hook.
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.