Datasheet

2−47
2.20.57 Interrupt Configuration Register A
Address C2h
Default 04h
7 6 5 4 3 2 1 0
Reserved
YCbCr enable
(VDPOE)
Interrupt A Interrupt polarity A
YCbCr enable (VDPOE):
0 = YCbCr pins are high impedance.
1 = YCbCr pins are active if other conditions are met (default).
Interrupt A (read-only):
0 = Interrupt A is not active on the external pin (default).
1 = Interrupt A is active on the external pin.
Interrupt polarity A:
0 = Interrupt A is active low (default).
1 = Interrupt A is active high.
Interrupt configuration register A is used to configure the polarity of the external interrupt terminal. When interrupt
A is configured as active low, the terminal is driven low when active and high-impedance when inactive (open
collector). Conversely, when the terminal is configured as active high, it is driven high when active and driven low
when inactive.
2.20.58 VDP Configuration RAM Register
Address C3h C4h C5h
Default DCh 0Fh 00h
Address 7 6 5 4 3 2 1 0
C3h Configuration data
C4h RAM address (7:0)
C5h Reserved
RAM
address 8
The configuration RAM data is provided to initialize the VDP with initial constants. The configuration RAM is 512 bytes
organized as 32 different configurations of 16 bytes each. The first 12 configurations are defined for the current VBI
standards. An additional 2 configurations can be used as a custom programmed mode for unique standards like
Gemstar.
Address C3h is used to read or write to the RAM. The RAM internal address counter is automatically incremented
with each transaction. Addresses C5h and C4h make up a 9-bit address to load the internal address counter with a
specific start address. This can be used to write a subset of the RAM for only those standards of interest. Registers
D0h−FBh must all be programmed with FFh, before writing or reading the configuration RAM. Full field mode (CFh)
must be disabled as well.
The suggested RAM contents are shown below. All values are hexadecimal.