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nubus/nubus_cb264.cpp, pds30_cb264.cpp: Better guess at screen parameters; note second XTAL and its probable use

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This commit is contained in:
AJR 2023-12-12 09:13:18 -05:00
parent 0bc20887a1
commit 3c1320f4b1
3 changed files with 9 additions and 9 deletions
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11
src/devices/bus/nubus/nubus_cb264.cpp
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@ -5,13 +5,14 @@
RasterOps ColorBoard 264 NuBus video card emulation
fixed resolution 640x480 NuBus video card, 1/2/4/8/24 bit color
1.5 MiB of VRAM, Bt473 RAMDAC, and two custom gate arrays.
1.5 MiB of VRAM, Bt473KPJ35 RAMDAC, and two custom gate arrays.
0xfsff6004 is color depth: 0 for 1bpp, 1 for 2bpp, 2 for 4bpp, 3 for 8bpp, 4 for 24bpp
0xfsff6014 is VBL ack: write 1 to ack
0xfsff603c is VBL disable: write 1 to disable, 0 to enable
Crystal (pixel clock) is 30.24 MHz
Crystal (pixel clock) is 30.24 MHz. A 12.3356 MHz XTAL is also present,
likely used only for 30 Hz interlaced NTSC output.
TODO:
- Figure out the vertical part of the CRTC registers and make the mode dynamic.
@ -73,7 +74,7 @@ void nubus_cb264_device::device_add_mconfig(machine_config &config)
{
screen_device &screen(SCREEN(config, "cb264_screen", SCREEN_TYPE_RASTER));
screen.set_screen_update(FUNC(nubus_cb264_device::screen_update));
screen.set_raw(30240000, 860, 0, 640, 524, 0, 480);
screen.set_raw(30.24_MHz_XTAL, 864, 0, 640, 525, 0, 480); // 35 kHz horizontal rate, 66.67 Hz vertical rate
PALETTE(config, m_palette).set_entries(256);
}
@ -244,13 +245,13 @@ void nubus_cb264_device::cb264_w(offs_t offset, u32 data, u32 mem_mask)
Vertical:
40: 2 - first line of active display?
44: 209 - last line of active display?
48: 20c - vtotal (524)
48: 20c - vtotal - 1? (525)
4c: f
Horizontal:
50: 27 - start of active display
54: c7 - end of active display (0xc7 - 0x27 = 160, 160 * 4 = 640)
58: d7 - htotal (860)
58: d7 - htotal/4 - 1? (864)
5c: 6b
*/

6
src/devices/bus/nubus/pds30_cb264.cpp
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@ -28,7 +28,7 @@ ROM_END
// GLOBAL VARIABLES
//**************************************************************************
DEFINE_DEVICE_TYPE(PDS030_CB264SE30, nubus_cb264se30_device, "pd3_c264", "RasterOps Colorboard 264/SE30")
DEFINE_DEVICE_TYPE(PDS030_CB264SE30, nubus_cb264se30_device, "pd3_c264", "RasterOps ColorBoard 264/SE30")
//-------------------------------------------------
@ -39,9 +39,7 @@ void nubus_cb264se30_device::device_add_mconfig(machine_config &config)
{
screen_device &screen(SCREEN(config, CB264SE30_SCREEN_NAME, SCREEN_TYPE_RASTER));
screen.set_screen_update(FUNC(nubus_cb264se30_device::screen_update));
screen.set_raw(25175000, 800, 0, 640, 525, 0, 480);
screen.set_size(1024, 768);
screen.set_visarea(0, 640-1, 0, 480-1);
screen.set_raw(30.24_MHz_XTAL, 864, 0, 640, 525, 0, 480);
}
//-------------------------------------------------

1
src/emu/xtal.cpp
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@ -208,6 +208,7 @@ const double XTAL::known_xtals[] = {
12'288'000, /* 12.288_MHz_XTAL Sega Model 3 digital audio board */
12'292'000, /* 12.292_MHz_XTAL Northwest Digitial Systems GP-19 */
12'324'000, /* 12.324_MHz_XTAL Otrona Attache */
12'335'600, /* 12.3356_MHz_XTAL RasterOps ColorBoard 264 (~784x NTSC line rate) */
12'432'000, /* 12.432_MHz_XTAL Kaneko Fly Boy/Fast Freddie Hardware */
12'472'500, /* 12.4725_MHz_XTAL Bonanza's Mini Boy 7 */
12'480'000, /* 12.48_MHz_XTAL TRS-80 Model II */