OUTS - OUTSB - OUTSW - OUTSD

INS - Output String from Port (80186+)

Transfers a byte, word or doubleword from “src” to the hardware port specified in DX.

For instructions with no operands the “src” is located at DS:SI and SI is incremented or decremented by the size of the operand or the size dictated by the instruction format.

When the Direction Flag is set SI is decremented, when clear, SI is incremented.

If the port number is in the range of 0-255 it can be specified as an immediate.
If greater than 255 then the port number must be specified in DX. Since the PC only decodes 10 bits of the port address, values over 1023 can only be decoded by third party vendor equipment and also map to the port range 0-1023.

see also INS

Usage:

	OUTS	dest,port
	OUTSB 
	OUTSW
	OUTSD			; (386+ only)

Modifies flags:

none

	Clocks				Size
Operands	808x	286	386	486	Bytes
port,src	-	5	14	17	1
port,src (PM)	-	-	8-28	10/32/30	1

386+ protected mode timings depend on privilege levels.

first number is the timing when:	CPL != IOPL
second number is the timing when:	CPL > IOPL
third number is the timing when:	virtual mode on 486 processor

see Instructions list, Instruction Timing, 8086 Architecture, CPU

2023/01/05 22:53 · frater