SC2200 NSC [National Semiconductor], SC2200 Datasheet - Page 350

• Manufacturer Part Number: SC2200
• Description: Thin Client On a Chip
• Manufacturer: NSC [National Semiconductor]

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Video Processor Module
Offset 8Ch-8Fh
Offset 90h-93h
Offset 94h-97h
Alpha values may be automatically incremented/decremented for successive frames. This register can be used to read the alpha values
that are being used in the current frame.
Offset 98h-3FFh
Offset 400h-403h
Selects various Video Processor modes.
31:18
31:28
27:16
15:11
31:24
23:16
15:8
10:0
15:8
27:4
7:0
7:0
Bit
17
16
31
30
29
28
3
2
Table 6-7. F4BAR0+Memory Offset: Video Processor Configuration Registers (Continued)
Description
Reserved
LOAD_ALPHA (Load Alpha Value). (Write Only) When set to 1, this bit causes the Video Processor to load the alpha
value (in bits [7:0], ALPHA3_VAL) at the start of the next frame.
ALPHA3_WIN_EN (Alpha Window 3 Enable). Enable bit for Alpha Window 3.
0: Disable Alpha Window 3.
1: Enable Alpha Window 3.
Valid only if video window is enabled (F4BAR0+Memory Offset 00h[0] = 1)
ALPHA3_INCR (Alpha Window 3 Increment). Specifies the alpha value increment/decrement. This is a signed 8-bit value
that is added to the alpha value for each frame. The MSB (bit 15) indicates the sign (i.e., increment or decrement). When
this value reaches either the maximum or the minimum alpha value (255 or 0) it keeps that value (i.e., it is not incre-
mented/decremented) until it is reloaded via bit 17 (LOAD_ALPHA).
ALPHA3_VAL (Alpha Window 3 Value). Specifies the alpha value to be used for this window.
Reserved. Set to 0.
VIDEO_X_REQ (Video Horizontal Request). Determines the horizontal (pixel) location at which to start requesting video
data out of the video FIFO. This value is calculated according to the following formula:
Value = Desired screen position + (H_TOTAL – H_SYNC_END) – 2.
Reserved
VIDEO_Y_REQ (Video Vertical Request). Determines the line number at which to start requesting video data out of the
video FIFO. This value is calculated according to the following formula:
Value = Desired screen position + (V_TOTAL – V_SYNC_END) + 1.
Reserved.
ALPHA3_VAL (Value for Alpha Window 3).
ALPHA2_VAL (Value for Alpha Window 2).
ALPHA1_VAL (Value for Alpha Window 1).
Video FIFO Underflow (Empty).
0: No underflow has occurred.
1: Underflow has occurred.
Write 1 to reset this bit.
Video FIFO OverFlow (Full).
0: No overflow has occurred.
1: Overflow has occurred.
Write 1 to reset this bit.
Reserved. Write as read.
Reserved. Write as read.
Reserved. Set to 0.
Reserved. Write as read.
Note:
Reserved. Write as read.
(Continued)
Video Processor Display Mode Register (R/W)
Alpha Window 3 Control Register (R/W)
Video Request Register (R/W)
Alpha Watch Register (RO)
Reserved
350
Reset Value: 001B0017h
Reset Value: 00000000h
Reset Value: 00000000h
Reset Value: 00000000h
Revision 3.0