com90c66 Standard Microsystems Corp., com90c66 Datasheet - Page 5

• Manufacturer Part Number: com90c66
• Description: Arcnet Controller/transceiver With At Interface And On-chip Ram Corporation
• Manufacturer: Standard Microsystems Corp.

PIN NO.
PLCC
66
67
52
53
54
30
72
70
nMemory Read nMEMR
nMemory
Write
Reset In
nROM Enable
nROM Select
Interrupt
Request
nZero Wait
State
nMemory
16-Bit Chip
Select
NAME
nMEMW
RESETIN
nENROM
nPROM
INTR
n0WS
nMEMCS16 Output. This active low signal is used to indicate that the
DESCRIPTION OF PIN FUNCTIONS
SYMBOL
Input.
microprocessor to indicate a Memory Read operation. A
low level on this pin when the COM90C66 is accessed
enables data from the internal RAM of the COM90C66 or
the PROM onto the data bus to be read by the host.
Input.
microprocessor to indicate a Memory Write operation. A
low pulse on this pin when the COM90C66 is accessed
enables data from the data bus into the internal RAM of
the COM90C66.
Input. This active high signal is the power on reset signal
from the host. It is used to activate the internal reset
circuitry within the COM90C66.
Input. This active low signal enables the decoding of the
external PROM. This signal also affects the timing of
IOCHRDY and the number of address lines used to
decode nMEMCS16. This signal is connected to a weak
internal pull-up resistor.
Output.
COM90C66 to enable the external 8-bit wide PROM or
the external register of the COM90C66.
Output.
COM90C66 when an enabled interrupt condition occurs.
INTR returns to its inactive state when the interrupt
status condition or the corresponding interrupt mask bit
is reset.
Output. This active low signal is used to force zero wait
state access cycles on the IBM PC Bus. This is an open-
drain signal.
provided by the system.
present data transfer is a 16-bit memory cycle.
COM90C66 can be configured to use A19-A17 or A19-
A11 to generate nMEMCS16.
signal. An external pull-up resistor is typically provided
by the system.
5
This active low signal is issued by the host
This active low signal is issued by the host
This active high signal is generated by the
This active low signal is issued by the
An external pull-up resistor is typically
DESCRIPTION
This is an open-drain
The