X88C64 Datasheet, PDF (4/14 Pages) Xicor Inc. – E2 Micro-Peripheral

X88C64
Data Memory Mode
This mode of operation allows both read and write
functions. The PSEN input is tied to V_IH or to V_CC
through a pull-up resistor. The ALE, RD, and WR inputs
are tied directly to the microcontroller’s ALE, RD, and
WR outputs.
Read
This operation is quite similar to the Program Memory
read. A HIGH to LOW transition on ALE latches the
MODE SELECTION
CE
PSEN
VCC
HIGH
LOW
LOW
LOW
X
X
LOW
HIGH
HIGH
RD
X
X
HIGH
LOW
HIGH
WR
X
X
HIGH
HIGH
addresses and the data will be output on the AD pins
after RD goes LOW (t_RLDV).
Write
A write is performed by latching the addresses on the
falling edge of ALE. Then WR is strobed LOW followed
by valid data being presented at the A/D₀–A/D₇ pins.
The data will be latched into the X88C64 on the rising
edge of WR. To write to the X88C64, a three-byte
command sequence must precede the byte(s) being
written. (See Software Data Protection.)
Mode
Standby
Standby
Program Fetch
Data Read
Write
I/O
High Z
High Z
D_OUT
DOUT
DIN
Power
Standby (CMOS)
Standby (TTL)
Active
Active
Active
3867 PGM T02.2
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