 typedef struct _CALL_GATE
}CALL_GATE,*PCALL_GATE;


Multics was the first user of call gates.The Honeywell 6180 had call gates as part of the architecture, but Multics simulated them on the older GE 645.OS/2 was an early user of Intel call gates to transfer between application code running in ring 3, privileged code running in ring 2, and kernel code in ring 0.