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Diffstat (limited to 'src/devices/video/upd7220.cpp')
-rw-r--r--src/devices/video/upd7220.cpp24
1 files changed, 18 insertions, 6 deletions
diff --git a/src/devices/video/upd7220.cpp b/src/devices/video/upd7220.cpp
index 1216839dce8..b4488be7052 100644
--- a/src/devices/video/upd7220.cpp
+++ b/src/devices/video/upd7220.cpp
@@ -3,6 +3,7 @@
/**********************************************************************
Intel 82720 Graphics Display Controller emulation
+ also known as NEC uPD7220
**********************************************************************/
@@ -22,7 +23,7 @@
- A5105 has a FIFO bug with the RDAT, should be a lot larger when it scrolls up.
Can be fixed with a DRDY mechanism for RDAT/WDAT;
- Some later SWs on PC-98 throws "Invalid command byte 05" (zettmj on Epson logo),
- actual undocumented command to reset something?
+ actual undocumented command to reset something or perhaps just check if upd7220 isn't really a upd72120 instead?
- honor visible area
- wide mode (32-bit access)
@@ -1730,18 +1731,29 @@ void upd7220_device::update_graphics(bitmap_rgb32 &bitmap, const rectangle &clip
if(im || force_bitmap)
{
- if(area >= 3) // TODO: most likely to be correct, Quarth (PC-98xx) definitely draws with area 2. We might see an area 3 someday ...
+ // according to documentation only areas 0-1-2 can be drawn in bitmap mode
+ // PC98 Quarth definitely needs area 2 for player section.
+ // TODO: what happens if combined area size is smaller than display height?
+ // documentation suggests that it should repeat from area 0, needs real HW verification (no known SW do it).
+ if(area >= 3)
break;
+ // PC98 madoum1-3 sets up ALL areas to a length of 0 after initial intro screen.
+ // madoum1: area 0 sad==0 on gameplay (PC=0x955e7), sad==0xaa0 on second intro screen (tower) then intentionally scrolls up and back to initial position.
+ // Suggests that length should be treated as max size if this occurs, this is also proven to be correct via real HW verification.
+ // TODO: check if text partition do the same.
+ if (len == 0)
+ len = 0x400;
+
if(!interlace)
len <<= 1;
for(y = 0; y < len; y++)
{
- /* TODO: again correct?
- Quarth (PC-98xx) doesn't seem to use pitch here and it definitely wants bsy to be /2 to make scrolling to work.
- Xevious (PC-98xx) wants the pitch to be fixed at 80, and wants bsy to be /1
- Dragon Buster (PC-98xx) contradicts with Xevious with regards of the pitch tho ... */
+ // TODO: not completely correct, all is drawn half size with real HW tests on pc98 msdos by just changing PRAM values.
+ // pc98 quarth doesn't seem to use pitch here and it definitely wants bsy to be /2 to make scrolling to work.
+ // pc98 xevious wants the pitch to be fixed at 80, and wants bsy to be /1
+ // pc98 dbuster contradicts with Xevious with regards of the pitch tho ...
uint32_t const addr = ((sad << 1) & 0x3ffff) + ((y / (mixed ? 1 : m_lr)) * (m_pitch << (im ? 0 : 1)));
for(int z = 0; z <= m_disp; ++z)
{