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author Bryan McPhail <bmcphail@vcmame.net>2017-06-27 17:02:07 -0400
committer Bryan McPhail <bmcphail@vcmame.net>2017-06-27 17:02:07 -0400
commit455fc201af1d74deda8b3defa08cf551d6be2ad3 (patch)
treeeb5677796312ee9fe5ad388a2b661384d6e08600
parentdad7fca1f75e1d1e6ba766ab15bbe0e4e905a24e (diff)
Add alternate revision of Cobra Command. Add correct palette weighting for all Dec8 games
-rw-r--r--src/mame/video/dec8.cpp35
1 files changed, 13 insertions, 22 deletions
diff --git a/src/mame/video/dec8.cpp b/src/mame/video/dec8.cpp
index 6f44238d372..cf46a380697 100644
--- a/src/mame/video/dec8.cpp
+++ b/src/mame/video/dec8.cpp
@@ -50,28 +50,19 @@ sprites.
Convert the color PROMs into a more useable format.
- Real Ghostbusters has two 1024x8 palette PROM.
- I don't know the exact values of the resistors between the RAM and the
- RGB output. I assumed these values (the same as Commando)
-
- bit 7 -- 220 ohm resistor -- GREEN
- -- 470 ohm resistor -- GREEN
- -- 1 kohm resistor -- GREEN
- -- 2.2kohm resistor -- GREEN
- -- 220 ohm resistor -- RED
- -- 470 ohm resistor -- RED
- -- 1 kohm resistor -- RED
- bit 0 -- 2.2kohm resistor -- RED
-
- bit 7 -- unused
- -- unused
- -- unused
- -- unused
- -- 220 ohm resistor -- BLUE
- -- 470 ohm resistor -- BLUE
- -- 1 kohm resistor -- BLUE
- bit 0 -- 2.2kohm resistor -- BLUE
-
+ Real Ghostbusters has two 1024x8 palette PROM, other games in this driver
+ use palette RAM.
+
+ Real Ghostbusters, Cobra Command, Gondomania, Oscar at least are confirmed
+ to use two custom resistor packs marked DECO RM-C3 to convert the digital
+ palette for analog output.
+
+ Each pack contains two channels with resistor values of 220 ohms,
+ 470 ohms, 1 kohm, 2.2 kohm and 4.8 kohm, however the highest resistance is
+ not used as these games are only 4 bits per channel.
+
+ This leads to weightings per bit of 0xe, 0x1f, 0x43, 0x8f.
+
***************************************************************************/
PALETTE_INIT_MEMBER(dec8_state,ghostb)