INT 21 P - Phar Lap 386/DOS-Extender VMM v3.0 - READ/WRITE LDT DESCRIPTOR AX = 2531h BX = segment selector ECX = direction (00h read, 01h write) DS:EDX -> 8-byte buffer for descriptor contents Return: CF clear if successful CF set on error EAX = error code 81h invalid selector 82h DPMIsee DOS Protected-Mode Interface running, or not a code or data segment