the project i'm working of must use a pc-keyboard. when i'm testing the project everythings seems to work ok. including the pc-keyboard. even when 1 press 2 letters simultaniously. the correct characters appears on the screen. no problem so far.

in an other routine i want to increase or decrease a value when i press the up or down keys. but when 1 press these keys at the same time my program doesn't respond any more.

the keyboard is attached to an interrupt port. does someone knows where i can find a sollution for this problem or how to solve this problem??

thanks in advance