Lucent Technologies MN10285K User Manual

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The graphics layer contains tiled images. In the 16-color mode, each 4-bit dot on 

a tile can display one of 16 colors. Each tile can use either of two available color 
palettes, allowing a total of 32 colors in one display. The graphics layer also 

supports 2-, 4-, and 8-color modes. All the tiles in a single display screen must be 
in the same color mode. (For instance, an 8-color-mode tile cannot be displayed 

at the same time as a 16-color-mode tile.) The size of one tile is 16W x 16H 
pixels in standard mode and 16W x 18H pixels in extended mode.

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The cursor layer displays an icon indicating the position of the next entry. One 
display screen displays only one cursor (tile). The ROM data and color palettes 

for the tile are the same as those of the graphics layer. The size of one tile is 16W 
x 16H pixels in standard mode and 32W x 32H pixels in extended mode.

When you are not using the 
DAC, set the COMP and IREF 

pins for the DAC to H.

To set up the output pins, enable the OSD output pins in the I/O registers. Select 
DAC or digital output for RGB and YM. Set the YS polarity.

The microcontroller writes display data to be sent to the OSD control registers 
and the VRAM, which is assigned to internal RAM space. The control registers 

(CRAMEND and GRAMEND) hold the end address of the data in the VRAM.

After a reset clears, the system 

clock supply to the OSD stops. 

To operate the OSD, you must 
first set the OSDPOFF bit of 

PCNT0 (x’00FF90’)to 1. 

Display data stored in the VRAM transfers automatically (through) a DMA 
transfer) from the internal RAM to the OSD as the display approaches its 

specified position. The microcontroller is suspended while the data is transferred 
on the bus. See section 7.10, “DMA and Interrupt Timing,” on page 185, for 

more information on this timing.

The two MSBs of the transferred data contain one or more of the following ID 

codes:

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1.

Character code

CC

2.

Color control code (normal mode)

COL

3.

Color control code (closed-caption mode)

COL

4.

Repeat character/blank code

CCB

5.

Character horizontal position code

CHP

6.

Character vertical position code

CVP

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1.

Graphic tile code

GTC

2.

Graphics horizontal position code

GHP

3.

Graphics vertical position code

GVP