z86131 ZiLOG Semiconductor, z86131 Datasheet - Page 19

• Manufacturer Part Number: z86131
• Description: Ntsc Line 21 Decoder
• Manufacturer: ZiLOG Semiconductor

ZiLOG
The XDSF mode is the FULL (information) display (Figure
11). This display shows the same information as the
GRAZE display and adds the program type as well the first
four program description rows (if transmitted). Although
XDS defines eight program description rows, the first four
are identified as containing the most important information.
The display of Program Description is limited to the first
four rows because eight rows would obscure much of the
screen and because more than four rows is not likely to be
sent due to the time required for transmission.
Because 15 scan lines per row mode are being used, rows
10–13 appears at the bottom of the screen.
When an XDS display mode has been selected, the infor-
mation is displayed as the appropriate packets are received.
The display remains on-screen as long as valid XDS data
continues to be received. If the 16 Second Erase Timer is
enabled (the default condition), the XDS display is erased
when no valid XDS data has been received for 16 Seconds.
If subsequent XDS data is received with displayable pack-
DS007200-TVX0199
OSD Row 1
OSD Row 2
OSD Row 3
OSD Row 10
OSD Row 11
OSD Row 12
OSD Row 13
Figure 10. XDSG (Graze) Mode Sample Display
OSD Row 1
Network Name
Program Name
Program Length
OSD Row 3
Network Name, Call Letters (Green)
Program
White)
Program Length, Program Type, Time In
Show (Cyan)
Program Description Row 1 (Yellow)
Program Description Row 2 (Yellow)
Program Description Row 3 (Yellow)
Program Description Row 4 (Yellow)
Name
OSD Row 2
Time in Show
Call Letters
(Italics,
Underline,
P R E L I M I N A R Y
ets, that information reappears on the screen. XDS data re-
covery can be active in the XDS display mode.
The XDS display mode is turned off by selecting a different
display mode.
Display Erase and Autoblanking
(Z86129 Only)
The display is erased in the TEXT mode by the Start Text
command (but the box is maintained) and in the CAPTION
mode by the Erase Displayed Memory (EDM) command.
The non-displayed memory can be erased by the Erase Non-
displayed Memory (ENM) command.
Four other events can also cause the display to be erased.
1. A change in the display mode, such as from CC1 to
2. A loss of video lock, such as on a channel change,
3. The third action that clears the displayed memory is
T1, CC1 to XDSF, and so forth, clears the memory and
hence the display.
causes the screen to be cleared. The current active dis-
play mode does not change. For example if CC1 was
selected and ON before the channel change the device
remains in the CC1/ON state after channel change.
the activation of the autoblanking circuit. The auto-
blanking circuit monitors the presence of a Line 21
waveform in the video field corresponding to the data
channel selected for display. The decoder is held in the
Decoder OFF (TV) state until a Line 21 waveform is
continuously detected for a period of 0.5 seconds.
When a valid Line 21 waveform has been detected for
0.5 seconds, and assuming that the user has selected
the Decoder ON state, the normal display for the data
OSD Row 1
Figure 11. XDSF Mode Sample Display
Program Length
Program Description information goes
here on OSD rows 10, 11
Network Name
Program Name
OSD Row 3
OSD Row 2
Time in Show
NTSC Line 21 Decoder
Call Letters
12 and,
Z86129/130/131
13
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