Vi-4-2. Monochrome Display Adapter Board - Canon A-200 series Service Manual

• RES (Reset)
This signal resets the CRTC externally. When this terminal is LOW, following things will occur:
. 1. The counter in the CRTC will be reset and stops operation.
2. All output signals other than DO through D7 signals become LOW.
3. The status of both address and control registers do not affect with the RES signal. The CPU
can access these registers even when the CRTC is in RESET mode.
• ClK (Character Clock)
This terminal is the fundamental clock input for any operation of the CRTC.
• HSYNC (Horizontal Synchronous)
This terminal outputs the H-sync. signal to the CRT.
• VSYNC (Vertical Synchronous)
This terminal outputs the V-sync. signal to the CRT.
• DISPTMG (Display Timing)
This signal denotes one screen displaying period of the H-sync. and V-sync signals.
• MAO - MA13: Refresh Memory Address
These signals are memory address outputs for refreshing an information on the CRT at certain
period of time.
As for the color display adaptor board, the CRTC supports 8-display pages.
• RAO - RA4: Raster Address
This signal is a raster select signal for the character generator.
• CUDISP (Cursor Display)
This video signal is used for displaying a cursor sign on the CRT monitor. It is inhibited when
the DISPTMG signal is LOW.
VI-4-2. Monochrome Display Adaptor Board
The monochrome display adaptor board is equipped with the A-200 Model M1 and M2. Gener ­
ally, this board has following specifications.
*
Displays 80 x 25 characters in one screen
*
9 x 14 pixels for one character box
*
7 x 9 pixels for one character
* Can drive an 18kHz-monochrome display monitor
* With character attribute
*
Can display 256 different characters
*
Video signal: 16.257MHz maximum
* V-sync signal: 720 x 350 (H x V), 50Hz
* H-sync signal: 18.432kHz
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