3.6 ROM Flash and Memory Interface Signals

Table 3.12 describes the ROM Flash and Memory Interface signals.

Table 3.12 ROM Flash and Memory Interface Signals

Name

PQFP

BGA

Type

Strength

Description

 

 

 

 

 

 

MWE/

139

C7

O

4 mA

Memory Write Enable. This pin is used as a write

 

 

 

 

 

enable signal to an external flash memory.

 

 

 

 

 

 

MCE/

141

A7

O

4 mA

Memory Chip Enable. This pin is used as a chip

 

 

 

 

 

enable signal to an external EEPROM or flash

 

 

 

 

 

memory device.

 

 

 

 

 

 

MOE/

140

B7

O

4 mA

Memory Output Enable. This pin is used as an

 

 

 

 

 

output enable signal to an external EEPROM or

 

 

 

 

 

flash memory during read operations. It is also

 

 

 

 

 

used to test the connectivity of the LSI53C875A

 

 

 

 

 

signals in test mode.

 

 

 

 

 

 

MAC/_

77

L10

O

16 mA

Memory Access Control. This pin can be

TESTOUT

 

 

 

 

programmed to indicate local or system memory

 

 

 

 

 

accessed (non-PCI applications). It is also used to

 

 

 

 

 

test the connectivity of the LSI53C875A signals in

 

 

 

 

 

test mode.

 

 

 

 

 

 

MAS0/

137

A8

O

4 mA

Memory Address Strobe 0. This pin is used to

 

 

 

 

 

latch in the least significant address byte (bits [7:0])

 

 

 

 

 

of an external EEPROM or flash memory. Since

 

 

 

 

 

the LSI53C875A moves addresses eight bits at a

 

 

 

 

 

time, this pin connects to the clock of an external

 

 

 

 

 

bank of flip-flops which are used to assemble up to

 

 

 

 

 

a 20-bit address for the external memory.

 

 

 

 

 

 

MAS1/

136

B8

O

4 mA

Memory Address Strobe 1. This pin is used to

 

 

 

 

 

latch in the most significant address byte (bits

 

 

 

 

 

[15:8]) of an external EEPROM or flash memory.

 

 

 

 

 

Since the LSI53C875A moves addresses eight bits

 

 

 

 

 

at a time, this pin connects to the clock of an

 

 

 

 

 

external bank of flip-flops which assemble up to a

 

 

 

 

 

20-bit address for the external memory.

 

 

 

 

 

 

ROM Flash and Memory Interface Signals

3-11

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LSI 53C875A technical manual ROM Flash and Memory Interface Signals