MCD212 Motorola, MCD212 Datasheet - Page 30

• Manufacturer Part Number: MCD212
• Description: Video Decoder and System Controller(with JTAG)
• Manufacturer: Motorola

The VDSC is programmable on a line–by–line (DCA) and/or field–by–field (ICA) basis. The image
displayed by the VDSC is made up of four distinct, programmable graphics planes, as indicated in
Figure 5–1. The foremost is the cursor plane, behind which are two video planes (A and B), and behind
them is a background plane. The data for plane A is handled by CH#1, while CH#2 handles the B
plane data. The order in which graphics planes A and B are displayed is controllable via the plane
order register (hC2) through CH#1.
The VDSC is programmable for several pre–defined modes of display and contains two video start
address registers (VSR1 and VSR2) to locate the video displays within the DRAM address space. The
display logic reads words from the video display area and sends them to the display file decoder which
serializes the data, either nibble per nibble or byte per byte. This programmability and flexibility allows
the VDSC to do various special effects such as subscreens, windowing, mosaics, overlay and mixing,
and transparency, among others.
5.1
The VDSC supports NTSC monitor, NTSC TV, and PAL TV formats as well as providing a means to
display images in one format that were created in the other. This compatibility feature allows this part
to be used throughout the world. Also, interlace and non–interlace displays are supported.
5.1.1
NTSC is the North American and Japanese standard for broadcast TV. The display is made up of
525 horizontal lines, counted in the vertical direction, displayed 30 times in one second. NTSC Monitor
is a little–used standard in North America for in–studio use on monitors. It is also made up of
525 horizontal lines.
PAL is the European standard for broadcast TV. Its display is made up of 625 horizontal lines, counted
in the vertical direction, but only displayed 25 times each second. Both systems allow for an image (or
frame) to be made up of two fields, an odd and an even field. The field rate is twice the frame rate
(60 Hz for NTSC and 50 Hz for PAL). Although each frame is made up of 525/625 lines, only 480/560
are visible on the screen.
MOTOROLA
IMAGE FORMATS
NTSC/PAL
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Figure 5–1. Four Video Planes of the Displayed Image
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IMAGE DISPLAY CONTROL
MCD212
BACKGROUND/EXTERNAL VIDEO
GRAPHICS PLANE B
CURSOR PLANE
GRAPHICS PLANE A
5
5–1