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bus/nubus: Updated Mac Display Card TODO notes.

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This commit is contained in:
Vas Crabb 2022-06-25 06:07:42 +10:00
parent 923ef2c25d
commit 5f751410ac
1 changed files with 11 additions and 7 deletions
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18
src/devices/bus/nubus/nubus_48gc.cpp
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@ -2,16 +2,21 @@
// copyright-holders:R. Belmont, Vas Crabb
/***************************************************************************
Apple 4*8 Graphics Card (model 630-0400) emulation
Apple 8*24 Graphics Card emulation (cards have the same framebuffer chip
w/different ROMs and RAMDACs, apparently)
Apple Macitosh Display Card 4•8 (model 630-0400)
Apple Macitosh Display Card 8•24
Cards have the same framebuffer, CRTC and clock synthesizers, but use
different RAMDACs and ROMs.
Monitor type changes take effect on had reset. The 8•24 defaults to the
“Page-White Gamma” profile for the 21" and 16" color monitors, which
affects white balance. Use the Monitors control panel to switch to the
“Uncorrected Gamma” profile if you don’t like it.
TODO:
* Work out why some monitors need magic multiply or divide by two to
get the right RAMDAC/CRTC clocks - inferring it from the reference
clock modulus is definitely wrong.
* The 8•24 card uses a strange off-white palette with some monitors,
including the 21" and 16" RGB displays.
* Interlaced modes.
***************************************************************************/
@ -472,11 +477,10 @@ void jmfb_device::update_crtc()
width >>= 2;
break;
}
XTAL const pixclock = 20_MHz_XTAL / m_modulus * m_multiplier / (1 << m_pdiv);
screen().configure(
htotal, vtotal,
rectangle(0, width - 1, 0, height - 1),
attotime::from_ticks(htotal * vtotal, pixclock).attoseconds());
attotime::from_ticks(htotal * vtotal, pixclk).attoseconds());
// TODO: determine correct timing for vertical blanking interrupt
m_timer->adjust(screen().time_until_pos(height - 1, 0));