80C186EB/80C188EB, 80L186EB/80L188EB
Table 3. Pin Descriptions (Continued)
Pin Pin Input Output
Description
Name Type Type States
DT/R O Ð H(Z) Data Transmit/Receive output controls the direction of a
bi-directional buffer in a buffered system. DT/R
is only
R(Z)
available for the PLCC package.
P(X)
LOCK O Ð H(Z) LOCK output indicates that the bus cycle in progress is not
to be interrupted. The processor will not service other bus
R(WH)
requests (such as HOLD) while LOCK
is active. This pin is
P(1)
configured as a weakly held high input while RESIN
is
active and must not be driven low.
HOLD I A(L) Ð 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.
HLDA O Ð H(1) HoLD Acknowledge output to indicate that the processor
has relinquished control of the local bus. When HLDA is
R(0)
asserted, the processor will (or has) floated its data bus
P(0)
and control signals allowing another bus master to drive the
signals directly.
NCS O Ð H(1) Numerics Coprocessor Select output is generated when
accessing a numerics coprocessor. NCS is not provided on
(N.C.) R(1)
the QFP or SQFP packages. This signal does not exist on
P(1)
the 80C188EB/80L188EB.
ERROR I A(L) Ð ERROR input that indicates the last numerics coprocessor
operation resulted in an exception condition. An interrupt
(N.C.)
TYPE 16 is generated if ERROR
is sampled active at the
beginning of a numerics operation. ERROR
is not provided
on the QFP or SQFP packages. This signal does not exist
on the 80C188EB/80L188EB.
PEREQ I A(L) Ð CoProcessor REQuest signals that a data transfer
between an External Numerics Coprocessor and Memory is
(N.C.)
pending. PEREQ is not provided on the QFP or SQFP
packages. This signal does not exist on the 80C188EB/
80L188EB.
UCS O Ð H(1) Upper Chip Select will go active whenever the address of
a memory or I/O bus cycle is within the address limitations
R(1)
programmed by the user. After reset, UCS
is configured to
P(1)
be active for memory accesses between 0FFC00H and
0FFFFFH.
LCS O Ð H(1) Lower Chip Select will go active whenever the address of
a memory bus cycle is within the address limitations
R(1)
programmed by the user. LCS
is inactive after a reset.
P(1)
P1.0/GCS0 O Ð H(X)/H(1) These pins provide a multiplexed function. If enabled, each
pin can provide a Generic Chip Select output which will go
P1.1/GCS1
R(1)
active whenever the address of a memory or I/O bus cycle
P1.2/GCS2
P(X)/P(1)
is within the address limitations programmed by the user.
P1.3/GCS3
When not programmed as a Chip-Select, each pin may be
P1.4/GCS4
used as a general purpose output Port. As an output port
P1.5/GCS5
pin, the value of the pin can be read internally.
P1.6/GCS6
P1.7/GCS7
NOTE:
Pin names in parentheses apply to the 80C188EB/80L188EB.
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