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 executi on in Real Mode will result in exception 6
(invalid opcode).
b. Exception 13 fault (general prote ction) will occur in Rea l Mode if an op erand refe rence 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 o ccur in Rea l M ode if an ope rand re fe ren ce is ma de
that partially or fully extends b eyond the maximum SS limit.
c. This instruction may be executed in Real Mode, its purpose is primarily to initiali ze the CPU for
Protected Mode.
Notes d through g apply to Real Addre ss 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 (multip li er).
Clock counts given are minimum to maximum. To calculate actual clocks use this formula:
Actual Clock = if m < > 0 then max ([log2 |m| ], 3) + b clo cks:
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 registe r
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