November 18, 2002

Am29F010B

9

DEVICE BUS OPERATIONS

This section describes the requirements and use of the

device bus operations, which are initiated through the

internal command register. The command register itself

does not occupy any addressable memory location.

The register is composed of latches that store the com-

mands, along with the address and data information

needed to execute the command. The contents of the

register serve as inputs to the internal state machine.

The state machine outputs dictate the function of the

device. The appropriate device bus operations table

lists the inputs and control levels required, and the re-

sulting output. The following subsections describe

each of these operations in further detail.

Table 1.

Am29F010B Device Bus Operations

Legend:

Notes:

1. Addresses are A16:A0.

2. The sector protect and sector unprotect functions must be implemented via programming equipment. See the “Sector Pro-

tection/Unprotection” section.

Requirements for Reading Array Data

To read array data from the outputs, the system must

control and selects the device. OE# is the output con-

trol and gates array data to the output pins. WE#

The internal state machine is set for reading array data

upon device power-up, or after a hardware reset. This

ensures that no spurious alteration of the memory con-

tent occurs during the power transition. No command is

necessary in this mode to obtain array data. Standard

microprocessor read cycles that assert valid addresses

on the device address inputs produce valid data on the

device data outputs. The device remains enabled for

read access until the command register contents are

altered.

See “Reading Array Data” for more information. Refer

to the AC Read Operations table for timing specifica-

tions and to the Read Operations Timings diagram for

table represents the active current specification for

reading array data.

Writing Commands/Command Sequences

To write a command or command sequence (which in-

cludes programming data to the device and erasing

sectors of memory), the system must drive WE# and

An erase operation can erase one sector, multiple sec-

tors, or the entire device. The Sector Address Tables

indicate the address space that each sector occupies.

A “sector address” consists of the address bits required

to uniquely select a sector. See the “Command Defini-

tions” section for details on erasing a sector or the

entire chip.

After the system writes the autoselect command se-

quence, the device enters the autoselect mode. The

system can then read autoselect codes from the inter-

nal register (which is separate from the memory array)

on DQ7–DQ0. Standard read cycle timings apply in this

mode. Refer to the “Autoselect Mode” and “Autoselect

Command Sequence” sections for more information.

tive current specification for the write mode. The “AC

Characteristics” section contains timing specification

tables and timing diagrams for write operations.

Operation

CE#

OE#

WE#

Addresses

(Note 1)

DQ0–DQ7

Read

L

L

H

Write

L

H

L

Standby

X

X

X

High-Z

Output Disable

L

H

H

X

High-Z

Hardware Reset

X

X

X

X

High-Z