28F010

Table 2 28F010 Bus Operations

Mode

CE

OE

WE

Read

Data Out

Output Disable

XX

Tri-State

READ-ONLY

Standby

XX

X

X

Tri-State

Data e 89H

Data e B4H

Read

READWRITE

Output Disable

XX

Tri-State

XX

X

X

Tri-State

Write

NOTES

2 Manufacturer and device codes may also be accessed via a command register write sequence Refer to Table 3 All other

addresses low

6 Refer to Table 3 for valid Data-In during a write operation

tents of the register default to the read command

making the 28F010 a read-only memory In this

mode the memory contents cannot be altered

Or the system designer may choose to ‘‘hardwire’’

available In this case all Command Register func-

tion) The 28F010 is designed to accommodate ei-

ther design practice and to encourage optimization

of the processor-memory interface

The two-step programerase write sequence to the

Command Register provides additional software

write protections

BUS OPERATIONS

Read

The 28F010 has two control functions both of which

must be logically active to obtain data at the out-

puts Chip-Enable (CE ) is the power control and

should be used for device selection Output-Enable

(OE ) is the output control and should be used to

gate data from the output pins independent of de-

vice selection Refer to AC read timing waveforms

used to access array data to output the Intelligent

Identifier codes and to access data for program

operation can only access the array data

Output Disable

With OE

device is disabled Output pins are placed in a high-

impedance state

Standby

With CE

at a logic-high level the standby opera-

tion disables most of the 28F010’s circuitry and sub-

stantially reduces device power consumption The

outputs are placed in a high-impedance state inde-

pendent of the OE

signal If the 28F010 is dese-

lected during erasure programming or program

erase verification the device draws active current

until the operation is terminated

Intelligent Identifier Operation

The Intelligent Identifier operation outputs the manu-

facturer code (89H) and device code (B4H) Pro-

gramming equipment automatically matches the de-

vice with its proper erase and programming algo-

rithms

7