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author couriersud <couriersud@arcor.de>2015-04-24 01:10:37 +0200
committer couriersud <couriersud@arcor.de>2015-04-24 01:10:37 +0200
commite08ddc8cad0d30ca3490fca8689f8fe4a87674b1 (patch)
tree18dcd47cdd62990f1891b7e9ddf965bf9ad06c0e
parent5a4269232b9cada4a30579001393417b89154996 (diff)
Properly document address deconding for GFX roms in cardline.
[Couriersud]
-rw-r--r--src/mame/drivers/cardline.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/src/mame/drivers/cardline.c b/src/mame/drivers/cardline.c
index 5ecfc3c57c5..1ee1cfc6b71 100644
--- a/src/mame/drivers/cardline.c
+++ b/src/mame/drivers/cardline.c
@@ -97,7 +97,15 @@ MC6845_UPDATE_ROW( cardline_state::crtc_update_row )
gfx_ofs = 0;
- if(m_video&2)
+ // bits 0 and 1 seem to be chip select lines. None of those selected
+ // most likely would put the output lines into a floating (threestate)
+ // state. The next statement doesn't add functioality but documents
+ // how this works.
+
+ if(m_video & 1)
+ gfx_ofs = 0;
+
+ if(m_video & 2)
gfx_ofs = 0x1000;
gfx = memregion("gfx1")->base();