SYSTEM INT1: Difference between revisions

Latest revision as of 05:28, 28 February 2017

The SYSTEM_INT1 call is the system ROM's v-blank interrupt routine.

It has its own frame counter (BIOS_INT1_FRAME_COUNTER, $10FDD4) and a flag to skip MESS_OUT and SYSTEM_IO (BIOS_INT1_SKIP, $10FEE3).

@@ Line 1: / Line 1: @@
-== [[BIOSF_VBL]] ($C0044A): Multiple purpose VBL routine ==
+== [[SYSTEM_INT1]] ($C00438): Multi-purpose VBL call ==
-Sets values in RAM according to buttons states, checks CDDA commands, probably other things... Always (?) called each frame by games.
+The SYSTEM_INT1 call is the [[system ROM]]'s v-blank [[68k interrupts|interrupt]] routine.
-Memory locations set (all 8bit):
+It will call [[MESS_OUT]] and [[SYSTEM_IO]].
-<pre>
-BIOS_P1CURRENT     $10FD95 Joystick 1 state
-BIOS_P1PREVIOUS    $10FD96 Previous joystick 1 state
-BIOS_P1CHANGE      $10FD97 Joystick 1 state change (edges)
-BIOS_P1REPEAT      $10FD98 Joystick 1 repeat (edge, and strobe if held more than ? calls)
-BIOS_P2CURRENT     $10FD9B Joystick 2 state
+It has its own frame counter (BIOS_INT1_FRAME_COUNTER, $10FDD4) and a flag to skip [[MESS_OUT]] and [[SYSTEM_IO]] (BIOS_INT1_SKIP, $10FEE3).
-BIOS_P2PREVIOUS    $10FD9C Previous joystick 2 state
-BIOS_P2CHANGE      $10FD9D Joystick 2 state change (edges)
-BIOS_P2REPEAT      $10FD9E Joystick 2 repeat (edge, and strobe if held more than ? calls)
-BIOS_STATCURNT     Joystick 1/2 start/select state
-BIOS_STATCHANGE    Previous Joystick 1/2 start/select state
-</pre>
-Bit definitions: see [[Joypad]]
 [[Category:BIOS calls]]