SPC8106 S-MOS Systems, SPC8106 Datasheet - Page 165

• Manufacturer Part Number: SPC8106
• Description: LCD/CRT VGA CONTROLLER
• Manufacturer: S-MOS Systems

The internal sprite palette operates similarly to the external palette supported in the 477 RAM-
DAC. When the RS2 bit (AUX[0B] bit 3) is set to 1, accesses to the internal Look Up Table (LUT)
are disabled and accesses to the internal sprite palette are enabled for index values 0Ch through
0Fh. The sprite palette is accessed in the same manner as the internal LUT, the only difference
being the RS2 value.
This duplicates the functionality of the external RAMDAC and allows the sprite palettes for the
CRT and the LCD to be written simultaneously, reducing the amount of code required (provided
that the OL[0:1] and OL23 outputs are connected to the external RAMDAC and that MD[13] = 0
on the falling edge of RESET to allow use of the 477 RAMDAC’s overlay registers). If the
SPC8106 is set to operate with a color LCD, then the internal sprite palette values will match
those of the external overlay registers. If the SPC8106 is set to operate with a monochrome LCD,
then the color value written to the 477 overlay palette will be internally gray scaled using the same
NTSC encoding used in the SPC8106 internal palette.
When AUX[0B] bit 7 = 1 writes to this register are disabled.
SPC8106
RS2 Bit
AUX[0B]
bit 3
Internal Sprite Palette
Sprite Palette Entry 0 (and overlay register 0) is the hardware cursor Background Color, when
Hardware Cursor is enabled. Similarly, Sprite Palette Entry 1(and overlay register 1) is the hard-
ware cursor Foreground Color, when Hardware Cursor is enabled.
411-1.0
0
0
1
1
1
Ext DAC
Read Select
AUX[0B]
bit 2
S-MOS Systems, Inc. • Tel: [phone] • Fax: [phone] • http://www.smos.com
0
1
0
1
X
LUT
Index
0C-0Fh
0C-0Fh
00-FFh
00-FFh
00-0Bh
10-FFh
Table 0-67 Palette Location Accesses
Palette Location Accessed
(Writes)
internal LUT and external
RAMDAC VGA palette registers
internal LUT and external
RAMDAC VGA palette registers
internal Sprite Palette Entries 0-3
and external RAMDAC overlay
register 0Ch-0Fh
internal Sprite Palette Entries 0-3
and external RAMDAC overlay
register 0Ch-0Fh
n/a
X12-SP-001-07
Palette Location Accessed
(Reads)
internal VGA LUT registers
external RAMDAC VGA palette
internal Sprite Palette Entry 0Ch-
0Fh
external RAMDAC overlay register
0Ch-0Fh
n/a
Hardware Functional Specification
SP1-123