80C186EC/188EC, 80L186EC/188EC
Table 2. Pin Descriptions (Continued)
Pin
Input
Type
Output
States
Pin Name
Pin Description
Type
A18/S5
A17/S4
A16/S3
(A15:8)
I/O
A(L)
H(Z)
R(WH)
I(0)
These pins drive address information during the address
phase of the bus cycle. During T2 and T3 these pins drive
status information (which is always 0 on the 80C186EC).
These pins are used as inputs during factory test; driving
these pins low during reset will cause unspecified operation.
On the 80C188EC, A15:8 provide valid address information
for the entire bus cycle.
P(0)
AD15/CAS2
AD14/CAS1
AD13/CAS0
I/O
S(L)
H(Z)
R(Z)
I(0)
These pins are part of the multiplexed ADDRESS and DATA
bus. During the address phase of the bus cycle, address bits
15 through 13 are presented on these pins and can be
latched using ALE. Data information is transferred during the
data phase of the bus cycle. Pins AD15:13/CAS2:0 drive the
82C59 slave address information during interrupt
acknowledge cycles.
P(0)
AD12:0
(AD7:0)
I/O
O
S(L)
Ð
H(Z)
R(Z)
I(0)
These pins provide a multiplexed ADDRESS and DATA bus.
During the address phase of the bus cycle, address bits 0
through 12 (0 through 7 on the 80C188EC) are presented on
the bus and can be latched using ALE. Data information is
transferred during the data phase of the bus cycle.
P(0)
S2:0
H(Z)
R(1)
I(1)
Bus cycle Status are encoded on these pins to provide bus
transaction information. S2:0 are encoded as follows:
P(1)
S2
S1
S0
Bus Cycle Initiated
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Interrupt Acknowledge
Read I/O
Write I/O
Processor HALT
Instruction Queue Fetch
Read Memory
Write Memory
Passive (No bus activity)
ALE
O
O
Ð
Ð
H(0)
R(0)
I(0)
Address Latch Enable output is used to strobe address
information into a transparent type latch during the address
phase of the bus cycle.
P(0)
BHE
(RFSH)
H(Z)
R(Z)
I(1)
Byte High Enable output to indicate that the bus cycle in
progress is transferring data over the upper half of the data
bus. BHE and A0 have the following logical encoding:
P(1)
Encoding (for 80C186EC/
80L186EC only)
A0
BHE
0
0
1
1
0
1
0
1
Word transfer
Even Byte transfer
Odd Byte transfer
Refresh operation
On the 80C188EC/80L188EC, RFSH is asserted low to
indicate a refresh bus cycle.
NOTE:
Pin names in parentheses apply to the 80C188EC/80L188EC.
11
INTEL [ INTEL ]
