80C186EC/80C188EC Microprocessor User's Manual

INTERRUPT CONTROL UNIT
Register Name: Initialization Command Word 4
Register Mnemonic:
Register Function:
ICW4 (accessed through MPICP1 and SPICP1)
Selects SFN Mode and AEOI Mode.
15 0
0
0
0
S
F
N
M
F
T
2
F
T
1
A
E
O
I
F
T
0
A1224-0A
Bit
Mnemonic
Bit Name
Reset
State
Function
SFNM
Special
Fully
Nested
Mode
X
Set to select Special Fully Nested Mode.
NOTE: Special Fully Nested Mode must be
used only in the master of a cascaded system.
AEOI
Automatic
EOI Mode
X
Set to select Automatic EOI Mode.
NOTE: Automatic EOI Mode must be used only
in the master of a cascaded system.
FT2:0
Factory
Test Mode
Select
XXX
These bits select factory test modes.
CAUTION: You must write the FT2:0 bits with
the following values. Failure to do so will cause
system failure and may cause system damage.
FT2 FT1 FT0
0 0 1
NOTE:
Reserved register bits are shown with gray shading. Reserved bits must be written
to a logic zero to ensure compatibility with future Intel products.
Figure 8-16. ICW4 Register
8-29