User's Manual

THE 80286 INSTRUCTION SET
CALL-Call Procedure
Opcode
Instruction
Clocks' Description
E8
cw CALL cw 7
Call near, offset relative to next instruction
FF
/2
CALL ew 7,mem=11 Call near, offset absolute at EA word
9A
cd
CALL cd 13,pm=26 Call inter-segment, immediate 4-byte address
9A
cd CALL cd
41 Call gate, same privilege
9A
cd CALL cd
82 Call gate, more privilege, no parameters
9A
cd
CALL cd
86+4X
Call gate, more privilege, X parameters
9A
cd
CALL cd 177
Call via Task State Segment·
9A
cd
CALL cd 182 Call via task gate
FF
/3
CALL ed
16,mem=29 Call inter-segment, address at EA doubleword
FF
/3
CALL ed
44
Call gate, same privilege
FF
/3
CALL ed 83
Call gate, more privilege, no parameters
FF
/3
CALL ed 90+4X
Call gate, more privilege, X parameters
FF
/3
CALL ed 180
Call
via Task State Segment
FF
/3
CALL ed
185
Call via task gate
·Add one clock for each byte in the next instruction executed.
FLAGS MODIFIED
None, except when a task switch occurs
FLAGS UNDEFINED
None
OPERATION
The CALL instruction causes the procedure named in the operand to be executed. When the procedure
is complete (a return instruction is executed within the procedure), execution continues at the instruc-
tion that follows the CALL instruction.
The CALL
cw form of the instruction adds modulo 65536 (the 2-byte operand) to the offset of the
instruction following the CALL and sets
IP to the resulting offset. The 2-byte offset of the instruction
that follows the CALL
is pushed onto the stack. It will be popped by a near RET instruction within
the procedure. The
CS register is not changed by this form.
The CALL
ew form of the instruction is the same as CALL cw except· that the operand specifies a
memory location from which the absolute 2-byte offset for the procedure is fetched.
The CALL
cd form of the instruction uses the 4-byte operand as a pointer to the procedure called.
The CALL
ed form fetches the long pointer from the memory location specified. Both long pointer
forms consult the AR byte
in the descriptor indexed by the selector part of the long pointer. The AR
byte can indicate one of the following descriptor types:
l. Code Segment-The access rights are checked, the return pointer is pushed onto the stack, and
the procedure
is jumped to.
B-23