Why is the trigger not working correctly?

Question

Electronics

If 2 diodes are connected, pressing buttons 1 and 2 does not record the trigger. But when you press 9 and 10 buttons, it writes 0 and 1 respectively to the first trigger, and does not write to the 4th trigger.

Answer 1

Pressing 1 and 2 buttons does not record the trigger

In which?

But, when you press 9 and 10 buttons , it records 0 and 1 respectively. to the first trigger, and does not write to the 4th trigger.

There are no first and fourth triggers on the diagram. There are U3 (A and B) and U4 (A and B). Yes, and button numbers - too.
If it is necessary that information from the two upper and two lower buttons gets into the trigger U4:B (assuming that at point "1", the common wire of the buttons is plus), then the diodes must be reversed. Now the information is duplicated in trigger U3:A.

Answer 2

To tell the truth, questions of technology logic of the Stone Age. Now ADC / DAC is solved by language coding, logical 0 or 1, as well as Or conditions, are set in the script, and there are options using register shift for all possible combinations of conditions.