
80C186EC/188EC, 80L186EC/188EC
Table 2. Pin Descriptions
(Continued)
Pin Name
Pin
Type
Input
Type
Output
States
Pin Description
PEREQ
I
A(L)
D
Processor Extension REQuest
signals that a data
transfer between an 80C187 Numerics Processor
Extension and Memory is pending. Systems not using an
80C187 must tie this pin to V
SS
. This signal does not exist
on the 80C188EC/80L188EC.
UCS
O
D
H(1)
R(1)
I(1)
P(1)
Upper Chip Select
will go active whenever the address of
a memory or I/O bus cycle is within the address range
programmed by the user. After reset, UCS is configured to
be active for memory accesses between 0FFC00H and
0FFFFFH.
LCS
O
D
H(1)
R(1)
I(1)
P(1)
Lower Chip Select
will go active whenever the address of
a memory or I/O bus cycle is within the address range
programmed by the user. LCS is inactive after a reset.
P1.0/GCS0
P1.1/GCS1
P1.2/GCS2
P1.3/GCS3
P1.4/GCS4
P1.5/GCS5
P1.6/GCS6
P1.7/GCS7
O
D
H(X)/H(1)
R(1)
I(X)/I(1)
P(X)/P(1)
These pins provide a multiplexed function. If enabled,
each pin can provide a
General purpose Chip Select
output which will go active whenever the address of a
memory or I/O bus cycle is within the address limitations
programmed by the user. When not programmed as a
Chip-Select, each pin may be used as a general purpose
output port.
T0OUT
T1OUT
O
D
H(Q)
R(1)
I(Q)
P(X)
Timer OUTput
pins can be programmed to provide single
clock or continuous waveform generation, depending on
the timer mode selected.
T0IN
T1IN
I
A(L)
A(E)
D
Timer INput
is used either as clock or control signals,
either level or edge sensitive depending on the
programming mode.
INT7:0
I
A(L)
A(E)
D
Maskable INTerrupt
input will cause a vector to a specific
Type interrupt routine. The INT6:0 pins can be used as
cascade inputs from slave 8259A devices. The INT pins
can be configured as level or edge sensitive.
INTA
O
D
H(1)
R(1)
I(1)
P(1)
INTerrupt Acknowledge
output is a handshaking signal
used by external 82C59A Programmable Interrupt
Controllers.
P3.5
P3.4
I/O
A(L)
H(X)
R(Z)
I(X)
H(X)
Bidirectional, open-drain port pins.
P3.3/DMAI1
P3.2/DMAI0
O
D
H(X)
R(0)
I(Q)
P(X)
DMA Interrupt
output goes active to indicate that the
channel has completed a transfer. DMAI1 and DMAI0 are
multiplexed with output only port functions.
NOTE:
Pin names in parentheses apply to the 80C188EC/80L188EC.
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