Accidentally we discovered a fairly serious error in the design of the Enterprise.
Totally do not mind if nothing is connected to the ports Control 1 and Control 2.
However, that EnterMice uses them.
It's about interference KB0..KB9 ports from keyboard.
If at one time is pressed only one key, then there is nothing wrong with (first figure).
However, if you press two keys simultaneously in the same column, the signal from the selected line will be transferred also to the line of second key (figure two).
In the Enterprise missing diodes separating the rows of the keyboard
Electrically nothing will happen (LS145 decoder has open collector outputs), but causes errors when reading from the external ports Control 1 and Control 2.
It turned out that my
security idea on the event of malfunction LS145 decoder, only worsens the situation.
I have to removed this fragment to "hide" these effects. However, in order to eliminate the cause should be within the Enterprise add diodes to each row of keys to press more than one key does not cause "collisions" (third figure).
