Trackball: Difference between revisions

Latest revision as of 18:22, 13 March 2017

Special controller only used in The Irritating Maze cabs.

Works the same way as an upside-down mechanical mouse. Uses two optical encoders for X and Y movement, handled by the SIT board.

A special system ROM is used (236-bios.sp1).

The counter values are read from REG_P1CNT:

Speed and direction are computed from the counter deltas.

@@ Line 1: / Line 1: @@
 [[File:Irrmaze_bios1.png|right]]
-Controller type used only by [[The Irritating Maze]].
+Special controller only used in [[The Irritating Maze]] cabs.
-Sort of an upside-down mechanical mouse, uses two optical encoders handled by the [[SIT board]].
+Works the same way as an upside-down mechanical mouse. Uses two optical encoders for X and Y movement, handled by the [[SIT board]].
-Special [[BIOS]]: 236-bios.sp1. X counter in {{Reg|REG_P1CNT}} when bit 0 of {{Reg|REG_POUTPUT}} is 0, otherwise Y counter.
+A special [[system ROM]] is used (236-bios.sp1).
-Refreshed every vblank unconditionnaly by this BIOS.
+The counter values are read from {{Reg|REG_P1CNT}}:
+* The X counter value when bit 0 of {{Reg|REG_POUTPUT}} is 0.
+* The Y counter value when bit 0 of {{Reg|REG_POUTPUT}} is 1.
+Speed and direction are computed from the counter deltas.
 [[Category:Cartridge systems]]