Sony DSC-D700 Service Manual page 98

Function description of main blocks
. Frame memory block (IC401, IC404, and IC405)
The frame memory consists of two 16M-byte DRAMs (IC404 and IC405).
This frame memory is controlled by the FA0 to FA9 (186-195), FRAS (179),
FCAS1 (180), FCAS2 (181), FWE (184), and FOE (185) signals output from
IC401. During release, video data of 1344 x 1024 or 640 x 480 pixels is written
according to the YUV 4:2:2 format.
. Video memory block (IC403 and IC405)
The video memory is 4M-byte VRAM (IC403). This video memory is controlled
by the VA0 to VA8 (42-50), VWE (57), VRAS (54), VCAS (55), and XVTRIG
(76) signals output from IC401. However, the read address of the VRAM SAM
port is controlled from the encoder by the serial communication (SDATA, SCLK,
ADRQ, and ADAK) between IC401 and IC402 (encoder).
Video data of 640 x 480 pixels is written in this VRAM according to the YUV 4:
2:0 format. Moreover, the character data stored in the buffer inside IC401 from
CPU is written in this VRAM during horizontal or vertical blanking period at
which no video data has been input.
. Encoder block (IC402)
The encoder is constituted by IC402. The YUV signal input from DRAM IC403
is encoded to an NTSC or PAL signal by digital processing and output through a
D/A converter as the Y and C signals contained in an analog signal. At that time,
the PAL signal converts the number of lines according to the picture size of 640 x
480 pixels and produces 640 x 570 pixels.
The character data read from VRAM IC403 is mixed with video data using this
encoder.
. Camera/video signal generator block (IC410 to IC416, and IC420 to IC423)
An oscillator circuit constituted by IC411 uses a reference video clock (24.545
MHz for NTSC and 24.375 MHz for PAL). A PLL circuit is constituted by IC412
to IC416 so as to synchronize a camera clock (29.670 MHz for NTSC and 24.750
MHz for PAL) with the reference video clock. In the PLL circuit, a frequency-
division circuit and a phase comparator are incorporated into IC401.
4-10 DSC-D700 (UC,CE)