DOS / Interrupts / 20

                 Interrupt 20h   Minix - Send/Receive Message

Input	DOS1	N	DOS2	N	DOS3	Y	DOS5	Y	Output
AX	Process ID of other Process								AX
BX	Pointer to Message								BX
CX	Instruction Code								CX
DX									DX
ES:DI									CF

Instruction Code:       1 = Send
                        2 = Receive
                        3 = Send & Receive

Notes:  The message contains the system call number (numbered
        as in V7 Unix) and the call parameter.