A "TRAP" IS THE METHOD THE PROCESSOR USED TO INFORM THE OPERATING SYSTEM THAT AN UNACCEPTABLE CONDITION HAS BEEN DETECTED.
TRAP ERRORS CAN BE CAUSED BY BOTH SOFTWARE AND HARDWARE. SOME OF THE ERRORS ARE DOUBLE FAULT, PROTECTION VIOLATION, ETC. THE MOST COMMON OF THESE IS A TRAP 0002 WHICH IS CAUSED BY AN NMI (NON-MASKED INTERRUPT). AN NMI CAN BE CAUSED BY A MEMORY PARITY ERROR, A CHANNEL ERROR, A BUS TIMEOUT, OR A WATCHDOG TIMER TIMOUT. THE MOST COMMON OF THESE IS MEMORY PARITY ERROR.
A TRAP 0002 MEMORY PARITY ERROR EXPERIENCED WHILE RUNNING OS/2 WILL BE ACCOMPANIED BY AN ERROR MESSAGE SCREEN WHICH WILL INFORM THE OPERATOR THAT THE ERROR WAS ON THE SYSTEM BOARD MEMORY, OR AN OPTION CARD (EXPANSION MEMORY).
NOTE 1. THE DATA REGISTERS DISPLAYED ON THE SCREEN BY OS/2 DO NOT CORRELATE TO AN ACTUAL FAILING MEMORY MODULE OR ADDRESS AND ARE INVALID FOR HARDWARE PROBLEM DETERMINATION. HOWEVER, THIS INFORMATION IS MEANINGFUL FOR SOME TYPES OF SOFTWARE PROBLEM DETERMINATION, SUCH AS TRAP 000D ERRORS.
NOTE 2. PS/2 SYSTEMS HAVE NO MEMORY ERROR CORRECTION HARDWARE, THEREFORE ANY PARITY ERROR WILL CAUSE A SYSTEM HALT WITH THE APPROPRIATE FAILURE INDICATIONS DEPENDING UPON THE OPERATING SYSTEM.