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-rw-r--r--src/mame/drivers/odyssey2.cpp12
1 files changed, 9 insertions, 3 deletions
diff --git a/src/mame/drivers/odyssey2.cpp b/src/mame/drivers/odyssey2.cpp
index 24980e784dd..a8ee2a172b4 100644
--- a/src/mame/drivers/odyssey2.cpp
+++ b/src/mame/drivers/odyssey2.cpp
@@ -54,14 +54,20 @@ XTAL notes (differs per model):
TODO:
- backgamm doesn't draw all the chars/sprites, it does multiple screen updates
and writes to the ptr/color registers, but does not increment the Y regs
-- 824x screen resolution is not strictly defined, height(243) is correct, but
+- screen resolution is not strictly defined, height(243) is correct, but
horizontal overscan differs depending on monitor/tv? see syracuse for overscan
- 824x on the real console, overlapping characters on eachother will cause
glitches (it is used to an advantage in some as-of-yet undumped homebrews)
- 8244(NTSC) is not supposed to show characters near the upper border, but
hiding them will cause bugs in some Euro games
-- 8245(PAL) video timing is not 100% accurate, though vtotal and htotal should
- be correct
+- according to tests, 8244 does not have a sound interrupt, but the Philips
+ service test cartridge for 8245 tests for it and fails if it did not get an irq
+- likewise, 8244 does not have a horizontal interrupt, but does 8245 have it?
+- tests done on 8244 suggests that Y(0xa4) is latched when reading X, but
+ that is inconsistent with the Philips service test cartridge: It reads X, Y, X,
+ then waits for 1 scanline, and reads Y again. It expects Y to change. Latching Y
+ will also cause video glitches to look different on some games when compared
+ to the real console, for example powerlrd.
- ppp(the tetris game) does not work properly on PAL, is this homebrew NTSC-only,
or is PAL detection going wrong? It does look like PAL/NTSC detection is working,
see internal RAM $3D d7. So maybe it is due to inaccurate PAL video timing.