Monochrome Display Adapter And Crt Check - Epson PC AX Technical Manual

DIAGRAKS AND REFERENCE MATERIALS
4. Monochrome Display Adapter and CRT Check
This module checks the monochrome display and its adapter.
First, select which check to perform from the menu.
HEV.A
+-----------------------------------------------------------------+
MONOCHROME ADAP TER AND CRT CHECK MENU
1 - Monochrome adapter check
2 - Attribute check
3 - Character set check
4 - Video check
5 - Sync check
6 - Run all above checks
o -
Exit
Enter selection number:
+-----------------------------------------------------------------+
(In case of test multiple times, only the monochrome adapter check
is performed.)
The remainder of this section describes each of the checking
procedures.
1) Monochrome Adapter Check
When the monochrome adapter check is selected, the program
displays following message:
+-----------------------------------------------------------------+
I I
I I
: MONOCHROME ADAP TER CHECK :
I I
I I
+-----------------------------------------------------------------+
a. A WRlTE/READ check is performed on the VRAM area used for the
monochrome display.
i) The Video Enable signal of the monochrome monitor is set to
OFF. Next, the test data "OOh" is written to and read from
the entire VRAM area ("BOOOOH" - "BOFAOH"), and a comparison
check is performed.
If the compared data do not match, the program displays
the address generating the mismatch, the written data, and
the read data.
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