FW82801EB Intel, FW82801EB Datasheet - Page 360

• Manufacturer Part Number: FW82801EB
• Manufacturer: Intel

Specifications of FW82801EB

• Lead Free Status / RoHS Status: Not Compliant

LPC Interface Bridge Registers (D31:F0)
9.4.9
360
OCW3—Operational Control Word 3 Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Bit
4:3
1:0
7
6
5
2
Reserved. Must be 0.
Special Mask Mode (SMM) — WO.
1 = The Special Mask Mode can be used by an interrupt service routine to dynamically alter the
Enable Special Mask Mode (ESMM) — WO.
0 = Disable. The SMM bit becomes a “don't care”.
1 = Enable the SMM bit to set or reset the Special Mask Mode.
OCW3 Select — WO. When selecting OCW3, bits 4:3 = 01
Poll Mode Command — WO.
0 = Disable. Poll Command is not issued.
1 = Enable. The next I/O read to the interrupt controller is treated as an interrupt acknowledge
Register Read Command — WO. These bits provide control for reading the In-Service Register
(ISR) and the Interrupt Request Register (IRR). When bit 1=0, bit 0 will not affect the register read
selection. When bit 1=1, bit 0 selects the register status returned following an OCW3 read. If bit 0=0,
the IRR will be read. If bit 0=1, the ISR will be read. Following ICW initialization, the default OCW3
port address read will be “read IRR”. To retain the current selection (read ISR or read IRR), always
write a 0 to bit 1 when programming this register. The selected register can be read repeatedly
without reprogramming OCW3. To select a new status register, OCW3 must be reprogrammed prior
to attempting the read.
00 = No Action
01 = No Action
10 = Read IRQ Register
11 = Read IS Register
system priority structure while the routine is executing, through selective enabling/disabling of
the other channel's mask bits. Bit 5, the ESMM bit, must be set for this bit to have any meaning.
cycle. An encoded byte is driven onto the data bus, representing the highest priority level
requesting service.
Master Controller
Slave Controller
Bit[6,0]=0, Bit[7,4:2]=undefined,
Bit[5,1]=1
–
–
0A0h
020h
Intel
Description
Attribute:
Size:
®
82801EB ICH5 / 82801ER ICH5R Datasheet
WO
8 bits