**up:**
Chapter 17 -- 80386 Instruction Set

**prev:** DEC Decrement by 1

**next:** ENTER Make Stack Frame for Procedure Parameters

# DIV -- Unsigned Divide

Opcode Instruction Clocks Description
F6 /6 DIV AL,r/m8 14/17 Unsigned divide AX by r/m byte
(AL=Quo, AH=Rem)
F7 /6 DIV AX,r/m16 22/25 Unsigned divide DX:AX by r/m
word (AX=Quo, DX=Rem)
F7 /6 DIV EAX,r/m32 38/41 Unsigned divide EDX:EAX by r/m
dword (EAX=Quo, EDX=Rem)

## Operation

temp := dividend / divisor;
IF temp does not fit in quotient
THEN Interrupt 0;
ELSE
quotient := temp;
remainder := dividend MOD (r/m);
FI;

*
*### Note

Divisions are unsigned. The divisor is given by the r/m operand.
The dividend, quotient, and remainder use implicit registers. Refer to
the table under "Description"
## Description

DIV performs an unsigned division. The dividend is implicit; only the
divisor is given as an operand. The remainder is always less than the
divisor. The type of the divisor determines which registers to use as
follows:
Size Dividend Divisor Quotient Remainder
byte AX r/m8 AL AH
word DX:AX r/m16 AX DX
dword EDX:EAX r/m32 EAX EDX

## Flags Affected

OF, SF, ZF, AR, PF, CF are undefined.
## Protected Mode Exceptions

Interrupt 0 if the quotient is too large to fit in the designated register
(AL, AX, or EAX), or if the divisor is 0; #GP(0) for an illegal memory
operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0)
for an illegal address in the SS segment; #PF(fault-code) for a page fault
## Real Address Mode Exceptions

Interrupt 0 if the quotient is too big to fit in the designated register
(AL, AX, or EAX), or if the divisor is 0; Interrupt 13 if any part of the
operand would lie outside of the effective address space from 0 to 0FFFFH
## Virtual 8086 Mode Exceptions

Same exceptions as in Real Address Mode; #PF(fault-code) for a page
fault

**up:**
Chapter 17 -- 80386 Instruction Set

**prev:** DEC Decrement by 1

**next:** ENTER Make Stack Frame for Procedure Parameters