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author Miodrag Milanovic <mmicko@gmail.com>2010-10-06 07:13:06 +0000
committer Miodrag Milanovic <mmicko@gmail.com>2010-10-06 07:13:06 +0000
commit7db585fdded305dc2d1803020c3d62661ece7c22 (patch)
tree08b77f686764003e52f61ecf29e84cb55e81b59a
parentf3f35e2af26fafac140d7ac7c13e76af90210d57 (diff)
v9938 - Set default value for status register 4 and 6 [Michael Zapf]
-rw-r--r--src/emu/video/v9938.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/src/emu/video/v9938.c b/src/emu/video/v9938.c
index ddefe3aa347..8c3939a04f5 100644
--- a/src/emu/video/v9938.c
+++ b/src/emu/video/v9938.c
@@ -576,6 +576,18 @@ void v9938_reset (int which)
vdp->INT = 0;
vdp->read_ahead = 0; vdp->address_latch = 0; /* ??? */
vdp->scanline = 0;
+ // MZ: The status registers 4 and 6 hold the high bits of the sprite
+ // collision location. The unused bits are set to 1.
+ // SR3: x x x x x x x x
+ // SR4: 1 1 1 1 1 1 1 x
+ // SR5: y y y y y y y y
+ // SR6: 1 1 1 1 1 1 y y
+ // Note that status register 4 is used in detection algorithms to tell
+ // apart the tms9929 from the v99x8.
+
+ // TODO: SR3-S6 do not yet store the information about the sprite collision
+ vdp->statReg[4] = 0xfe;
+ vdp->statReg[6] = 0xfc;
}
static void v9938_check_int (running_machine *machine)