INT 21 P - Phar Lap 386/DOS-Extender v4.0+ - READ/WRITE IDTsee Interrupt Descriptor Table DESCRIPTOR AX = 253Dh BL = interrupt number ECX = direction (0 = read, 1 = write) DS:EDX -> 8-byte buffer for descriptor Return: CF clear if successful DS:EDX filled if reading CF set on error EAX = error code (0082h if running under DPMIsee DOS Protected-Mode Interface) Desc: access hardware-level IDTsee Interrupt Descriptor Table rather than the internal 386/DOS-Extender shadow IDTsee Interrupt Descriptor Table Notes: this call will always fail under DPMIsee DOS Protected-Mode Interface because it is not possible to access the IDTsee Interrupt Descriptor Table the descriptor is not checked when writing this call can normally be used only by programs running in ring 0 because the processor does not allow an interrupt to be vectored to a less privileged ring