83Plus:Hooks:9BA8

Synopsis

Name: Trace Hook

Hook Pointer Block Address: 9BA8

Hook Enable BCALL: 4FF3

Hook Disable BCALL: 4FF6

Hook Call BCALL: 4FF9

Hook Active Flag: 0, (iy + 36h)

This hook allows you to change the actions that happen when tracing a graph.

These different values, passed in a, determines what the hook should do.

0: Unknown what this is used for, but it's called between the a=1 and a=4 hookcalls.
- b: contains the function that will be graphed y1=01 .. y0=0A or x1=01.. x6=06 or r1=01 .. r6=06 or u=01 .. w=03.
1: The trace cursor will move.
- Zero flag: clear to abort the move.
2: The trace cursor wants to move outside the screen and thus the graph will be (partially) redrawn.
3: The trace cursor blinks.
- Zero flag: Clear to stop the blinking
4: The trace cursor is (re)drawn
- Zero flag: Clear to abort the drawing of the cursor. (The blinking pixel in the middle will still blink at the position the cursor wasn't drawn)

This documentation is probably incomplete.