Intel 386 User Manual

Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
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6.6.3 PSRAM Interface
Pseudo SRAM (PSRAM) devices can be easily interfaced (Figure 6-17) to the Intel386 EX pro-
cessor. PSRAM devices have an interface that is similar to SRAM devices (They are also pin-
compatible in many cases). The two major differences between PSRAM and SRAM devices are:
• PSRAM devices require a CE# precharge (inactive) time between access cycles. Since the
Intel386 EX processor does not guarantee a minimum inactive time on it’s CSn# signals,
control logic is required to satisfy the PSRAM device’s CE# precharge time.
• PSRAM devices have a RFSH# input pin. This signal activates an internal refresh cycle.
The REFRESH# output of the Intel386 EX processor can be connected directly to the
PSRAM device’s RFSH# pin.
Figure 6-17. Intel386 EX Processor to PSRAM Interface
Intel386™ EX
Embedded
Processor
OE#

WE#

RFSH#
Note:
Control logic is necessary to satisfy the precharge time for the CE# signal of the
PSRAM. The precharge time is specified by the PSRAM manufacturer.
PSRAM
Address
Data
RD#

WR#

REFRESH#
Control
Logic
CE#
CS n #
A2854-02

Intel 386 Specifications

General

Architecture	x86
Clock Speed	12 MHz to 40 MHz
Transistor Count	275, 000
Data Bus Width	32-bit
Address Bus Width	32-bit
Instruction Set	x86
Introduced	1985
Maximum Memory	4 GB
Operating Modes	Real mode, Protected mode, Virtual 8086 mode
MMU	Yes
Voltage	5V
Model	Intel 386
Package	PGA
Process	1.5 μm to 1 μm