diff options
author | Miodrag Milanovic <mmicko@gmail.com> | 2010-10-06 07:13:06 +0000 |
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committer | Miodrag Milanovic <mmicko@gmail.com> | 2010-10-06 07:13:06 +0000 |
commit | 7db585fdded305dc2d1803020c3d62661ece7c22 (patch) | |
tree | 08b77f686764003e52f61ecf29e84cb55e81b59a | |
parent | f3f35e2af26fafac140d7ac7c13e76af90210d57 (diff) |
v9938 - Set default value for status register 4 and 6 [Michael Zapf]
-rw-r--r-- | src/emu/video/v9938.c | 12 |
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) |