Editing Apple Desktop Bus (section)

== Extended Protocol Specifications ==

=== Extended Keyboard Protocol ===

The Extended Keyboard Protocol distinguishes between left and right modifier keys:

{| class="wikitable" style="width:80%; text-align:center;"
|+'''Extended Keyboard Protocol (Handler ID $03)'''
! Register !! Format !! Description
|-
| 0 || 2 bytes || Two key events: 7-bit keycode + 1-bit up/down flag each
|-
| 1 || Undefined || Reserved for vendor use
|-
| 2 || 2 bytes || LED status and modifier key states
|-
| 3 || 2 bytes || Device address and handler ID
|}

'''Register 2 Extended Format:'''
* Bit 0: Num Lock LED (0=off, 1=on)
* Bit 1: Caps Lock LED
* Bit 2: Scroll Lock LED  
* Bit 3: Compose LED
* Bit 4: Kana LED
* Bit 5: Power LED
* Bit 6: Reserved
* Bit 7: Delete key state

'''Extended Keycodes:'''
* $32: Left Shift
* $38: Right Shift  
* $37: Left Command
* $3C: Right Command
* $3A: Left Option
* $3D: Right Option
* $36: Left Control
* $3E: Right Control

=== Extended Mouse Protocol ===

The Extended Mouse Protocol (Handler ID $04) supports multiple buttons and higher precision:

'''Standard Mouse Protocol (Handler ID $01):'''
* Register 0: 2 bytes
* Byte 0: Button state (bit 7) + X delta (bits 6-0, signed)
* Byte 1: Button state (bit 7) + Y delta (bits 6-0, signed)
* Resolution: 100±10 counts per inch
* Movement range: -64 to +63 per packet

'''Enhanced Resolution (Handler ID $02):'''
* Same format as standard protocol
* Resolution increased to 200±10 counts per inch

'''Extended Protocol Features:'''
* Support for up to 8 buttons
* 16-bit movement deltas
* Configurable resolution up to 400 CPI
* Scroll wheel support (vendor-specific)