80C186EA Datasheet, PDF (13/50 Pages) Intel Corporation – 16-BIT HIGH-INTEGRATION EMBEDDED PROCESSORS

80C186EA 80C188EA 80L186EA 80L188EA
Table 3 Pin Descriptions (Continued)
Pin
Pin Input Output
Name Type Type States
Description
WR QS1 O
ARDY
I
H(Z)
R(Z)
P(1)
WRite output signals that data available on the data bus are to be
written into the accessed memory or I O device In Queue Status
Mode QS1 provides queue status information along with QS0
A(L)
Asychronous ReaDY is an input to signal for the end of a bus cycle
S(L)
ARDY is asynchronous on rising CLKOUT and synchronous on falling
CLKOUT ARDY or SRDY must be active to terminate any processor
bus cycle unless they are ignored due to correct programming of the
Chip Select Unit
SRDY
I S(L)
DEN
O H(Z)
R(Z)
P(1)
Synchronous ReaDY is an input to signal for the end of a bus cycle
ARDY or SRDY must be active to terminate any processor bus cycle
unless they are ignored due to correct programming of the Chip Select
Unit
Data ENable output to control the enable of bidirectional transceivers
when buffering a system DEN is active only when data is to be
transferred on the bus
DT R
O
H(Z)
R(Z)
P(X)
Data Transmit Receive output controls the direction of a bi-
directional buffer in a buffered system DT R is only available on the
QFP (EIAJ) package and the SQFP package
LOCK
O
H(Z)
R(WH)
P(1)
LOCK output indicates that the bus cycle in progress is not to be
interrupted The processor will not service other bus requests (such
as HOLD) while LOCK is active This pin is configured as a weakly
held high input while RESIN is active and must not be driven low
HOLD
HLDA
I A(L)
HOLD request input to signal that an external bus master wishes to
gain control of the local bus The processor will relinquish control of
the local bus between instruction boundaries not conditioned by a
LOCK prefix
O
H(1) HoLD Acknowledge output to indicate that the processor has
R(0) relinquished control of the local bus When HLDA is asserted the
P(0) processor will (or has) floated its data bus and control signals allowing
another bus master to drive the signals directly
UCS
O
LCS
O
H(1) Upper Chip Select will go active whenever the address of a memory
R(1) or I O bus cycle is within the address limitations programmed by the
P(1) user After reset UCS is configured to be active for memory accesses
between 0FFC00H and 0FFFFFH During a processor reset UCS and
LCS are used to enable ONCE Mode
H(1) Lower Chip Select will go active whenever the address of a memory
R(1) bus cycle is within the address limitations programmed by the user
P(1) LCS is inactive after a reset During a processor reset UCS and LCS
are used to enable ONCE Mode
NOTE
Pin names in parentheses apply to the 80C188EA and 80L188EA
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