Circuit Description; Circuit Operations Of If-687 Board - Sony UP-D2500 Service Manual

SECTION 4
CIRCUIT DESCRIPTION
4-1. CIRCUIT OPERATIONS OF IF-687 BOARD
[Outline]
Main Functions of IF-687 Board
(1) Receives command data from the personal computer via the parallel interface.
(2) Sends command data to the personal computer via the parallel interface.
(3) Receives bit map image data from the personal computer via the parallel interface and writes in
the DRAM.
(4) Reads data from the DRAM during printing, and sends it to the PRT-11 board via the masking
table (in the case of UP-D2550 (For J)).
(5) Determines key inputs, LED lighting
Structure of IF-687 Board
(1) IEEE-1284 (Interactive parallel=Bi-Centronics) interface circuit
(2) DRAM and control circuit
(3) CPU
(4) Color adjustment, masking table
[UP-D2500 (For UC and CE) and UP-D2550 (For J)]
The UP-D2500 (For UC and CE) and UP-D2550 (For J) differ in the capacity of the image
memory mounted.
UP-D2500 (For UC and CE) 2 MB (IC107 only) For the screen of 1 color
UP-D2550 (For J) 4 MB (IC107, IC108) For the screen of 3 colors
With the UP-D2500 (For UC and CE), images are transferred before printing starts for Y, M, and
C in the printing operations of the printer driver.
Printing starts—Y transfer—Y printing—>M transfer—M printing—C transfer—>C
printing End
As masking is performed by the host computer, the printer is not equipped with the masking
ROMs IC105 and IC106.
During 155 dpi mode printing and 4-division and 16-division printing, masking is performed by
the host computer, and printing starts after all the data has been accumulated in the printer.
The UP-D2550 (For J) starts printing after accumulating all the data in the memory for the screen
of 3 colors.
Printing starts->RGB transfer—Y printing—M printing->C printing-End
RGB-YMC conversion and masking are performed by the printer.
UP-D2500(UC,CE)