Z86129 Datasheet, PDF (24/50 Pages) Zilog, Inc. – NTSC LINE 21 DECIDER

Z86129/130/131
NTSC Line 21 Decoder
PRELIMINARY
COMMANDS (Continued)
Caption and Text display modes and the proper command
code to activate them:
Table 9. Caption and Display Commands
CPTX
Command
CC1
CC2
CC3
CC4
T1
T2
T3
T4
CPTX Command Code
Decoder ON Decoder OFF
17h
16h
15h
14h
1Fh
1Eh
1Dh
1Ch
13h
12h
11h
10h
1Bh
1A
19h
18
XDS Display Mode and 16 Second Erase Timer
Commands
XDS DISP = 20h-27h. XDS Display commands are one
byte commands. These commands control the selection of
XDS display modes and the state of the 16 Second Erase
Timer. The 16 Second Erase Timer is active only for
Caption and XDS display modes. The 16 Second Erase
Timer has no affect on TEXT mode displays
Table 10. XDS Display Commands
XDS Display
XDS Display Command Code
Command
16 Sec Tmr ON 16 Sec Tmr OFF
XDSG
23h
27h
XDSF
21h
25h
16 Second Erase
20h
24h
Timer
Note: Changing the ON/OFF state of the 16 Second Erase
Timer has no affect on the current display mode in operation.
RDS1 = 40h-47h. RDS1 is a one-byte command used to
initiate a one-byte read sequence by moving the contents
of the register identified by the address field (AD00:02) of
the command to the output register. Addresses 0h-7h are
valid in the RDS1 command field AD00:02.
Bit CM7 CM6 CM5
0
1
0
W
W
W
CM4
0
W
CM3 CM2 CM1 CM0
0 AD02 AD01 AD00
W WWW
Figure 13. RDS1-Read One Byte (RDS1 = 40h-47h)
RDS2 = 60h-66h. RDS2 is a one byte command which is
used to initiate a two byte read sequence by moving the
contents of the two consecutive registers, starting with the
one identified by the address portion of the command
(AD00:AD02), to the output registers and setting the RD2
bit in the SS register. Only Addresses 0h-6h are valid in the
RDS2 command field AD00:02.
Bit 7
6
5
4
3
21
0
0
11
0
0 AD02 AD01 AD00
W WW W W W WW
Figure 14. RSD2-Read Two Bytes (RDS2 = 60h-66h)
Note: For XDS data recovery, when the XDS Filter
Register (see Internal Register section) is enabled for the
desired packets, the Z86129/130/131 will automatically
establish the two byte recovery mode and move the
recovered data bytes to the output register.
Read And Write Commands
Read Selects. There are two Read Select commands
(RDS1 and RDS2) in the Z86129/130/131. Each
command is one byte in size and indicates that a read
should take place. RDS1 specifies that one byte will be
read from the Z86129/130/131. Likewise, RDS2 indicates
that two bytes will be read.
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