The Interrupt descriptor table (IDT) is a hardware architected structure that comprises a table of gate descriptors, one for each interrupt vector. The low numbered entries are defined by the hardware architecture and dedicated to exception management.

Under OS/2 one IDT is allocated for the entire system except for VDMs in which multiple IDTs per VDM are possible. A VDM will allocate one IDT per DPMI client, but if it does not use DPMI then the common system IDT is used. When multiple IDTs are used in a VDM then only the entries not reserved for H/W exceptions and interrupts are allowed to differ.

The Kernel Debugger's V command may be used to intercept system exception handlers.

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