Intel 386 User Manual
Page 657
Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
E-20
NOTES:
Notes a through c apply to Real Address Mode only:
a.
This is a Protected Mode instruction. Attempted execution in Real Mode will result in exception 6
(invalid opcode).
b.
Exception 13 fault (general protection) will occur in Real Mode if an operand reference is made that
partially or fully extends beyond the maximum CS, DS, ES, FS, or GS limit, FFFFH. Exception 12 fault
(stack segment limit violation or not present) will occur in Real Mode if an operand reference is made
that partially or fully extends beyond the maximum SS limit.
c.
This instruction may be executed in Real Mode, its purpose is primarily to initialize the CPU for
Protected Mode.
Notes d through g apply to Real Address Mode and Protected Virtual Address Mode:
d.
The Intel386 SX CPU uses an early-out multiply algorithm. The actual number of clocks depends on
the position of the most significant bit in the operand (multiplier).
Clock counts given are minimum to maximum. To calculate actual clocks use this formula:
Actual Clock = if m < > 0 then max ([log
2
|m| ], 3) + b clocks:
if m = 0 then 3 + b clocks
In this formula, m is the multiplier, and
b = 9 for register to register
b = 12 for memory to register
table register
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 1
mod 0 0 1 r/m
9*
9*
b, c
h
SLDT = store local descriptor table
to register/memory
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 0
mod 0 0 0 r/m
N/A
2/2*
a
h
SMSW = store machine
status word
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 1
mod 1 0 0 r/m
2/2*
2/2*
b, c
h, l
STR = store task register
to register/memory
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 0
mod 0 0 1 r/m
N/A
2/2*
a
h
VERR = verify read access
register/memory
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 0
mod 1 0 0 r/m
N/A
10/11*
a
g, h, j, p
VERW = verify write
access
0 0 0 0 1 1 1 1
0 0 0 0 0 0 0 0
mod 1 0 1 r/m
N/A
15/16*
a
g, h, j, p
Table E-1. Instruction Set Summary (Sheet 19 of 19)
Instruction
Format
Clock Count
Notes
Real
Ad-
dress
Mode
or
Virtual
8086
Mode
Pro-
tected
Virtual
Ad-
dress
Mode
Real
Ad-
dress
Mode
or
Virtual
8086
Mode
Pro-
tected
Virtual
Ad-
dress
Mode