Intel 82555 manual Register 1 Status Register Bit Definitions, 10BASE-T

Networking Silicon — 82555

Bit(s)	Name		Description	Default	R/W
11	Power-Down	This bit sets the 82555 into a low power mode.		0	RW
		1	= Power-down enabled
		0	= Power-down disabled (normal operation)
10	Isolate	This bit allows the 82555 to electrically isolate the Media		0	RW
		Independent Interface. When the MII is isolated, the
		82555 does not respond to TXD[3:0], TXEN, and TXERR
		input signals. Also, the 82555 presents high impedance
		on its TXC, RXC, RXDV, RXERR, RXD[3:0], COL, and
		CRS output signals. In the TX mode, the 82555 responds
		to management transactions.
		1	= Electrically isolate MII
		0	= Normal operation
9	Restart Auto-	This bit restarts the Auto-Negotiation process and is self-		0	RW
	Negotiation	clearing.			SC
		1	= Restart Auto-Negotiation process
		0	= Normal operation
8	Duplex Mode	This bit controls the duplex mode when Auto-Negotiation		0	RW
		is disabled. If the 82555 reports that it is only able to
		operate in one duplex mode, the value of this bit shall
		correspond to the mode which the 82555 can operate.
		When the 82555 is placed in Loopback mode, the
		behavior of the PHY shall not be affected by the status of
		this bit, bit 8.
		1	= Full Duplex
		0	= Half Duplex
7	Collision Test	This bit will force a collision in response to the assertion		0	RW
		of the transmit enable signal.
		1	= Force COL
		0	= Do not force COL
6:0	Reserved	These bits are reserved and should be set to 0000000b.		0	RW

7.2.1.2Register 1: Status Register Bit Definitions

Bit(s)	Name		Description	Default	R/W
15	100BASE-T4	1 = 82555 able to perform 100BASE-T4		--	RO
		0	= 82555 not able to perform 100BASE-T4		P
14	100BASE-TX Full	1	= 82555 able to perform full duplex 100BASE-TX	--	RO
	Duplex	0	= 82555 not able to perform full duplex in repeater		P
		mode
13	100 Mbps Half	1	= 82555 able to perform half duplex 100BASE-TX	--	RO
	Duplex	0	= 82555 not able to perform 100BASE-TX		P
12	10 Mbps Full	1	= 82555 able to operate at 10 Mbps in full duplex	--	RO
	Duplex	mode			P
		0	= 82555 not able to operate in full duplex mode in
		10BASE-T
11	10 Mbps Half	1	= 82555 able to operate at 10 Mbps in half duplex	--	RO
	Duplex	mode			P
		0	= 82555 not able to operate in 10BASE-T
10:7	Reserved	These bits are reserved and should be set to 0000b.		0	RO

Datasheet 29