Quantum Data 801GC, 801GF, 801GX manual Checking a Display Code

Checking a

Display Code

Some computers and video controller cards look for the display codes and automatically adjust their hard- ware to output an appropriate video signal format for the display that is connected.

Problems can occur if a display outputs the wrong code and it is connected to a computer having an automatic format adjustment feature. The wrong sig- nal may be generated and the display may appear to be broken.

The 801G* is capable of checking the status of the code pins in its D-sub connectors. These pins are identified as M0 through M3 in table 5-1. Each sig- nal format in the 801G* can be independently set- up to test one or more of the display code pins. The formats also can be set-up with the expected code. The “Format” test image shows both the expected

Table 5-2

Display Code Values for all Sense Line Combinations

Code	M3	M2	M1	M0	Code	M3	M2	M1	M0
0	0	0	0	0	8	1	0	0	0
1	0	0	0	1	9	1	0	0	1
2	0	0	1	0	A	1	0	1	0
3	0	0	1	1	B	1	0	1	1
4	0	1	0	0	C	1	1	0	0
5	0	1	0	1	D	1	1	0	1
6	0	1	1	0	E	1	1	1	0
7	0	1	1	1	F	1	1	1	1

code and the code that is read as a single hexidecimal numbers. The following table shows the equivalent hex code values for all possible input combinations. A “0” indicates a grounded or logic low input and “1” indicates either a floating or logic high input

❖The 801G* merely reads and displays the code. It does not automatically select or modify signal format data based on the code.

Some of the built-in industry standard formats have been set-up to check for the proper codes. The fol- lowing tables list the formats and the expected iden- tification codes. The tables also show which pins need to be open (1) or grounded (0) to create the correct code.

Display Connection & Display Codes 5-7