W29C020

Publication Release Date: February 1998

- 5 -

Revision A3

Toggle Bit (DQ6)- Write Status Detection

In addition to data polling, the W29C020 provides another method for determining the end of a write

cycle. During the internal write cycle, any consecutive attempts to read DQ6 will produce alternating

0's and 1's. When the write cycle is completed, this toggling between 0's and 1's will stop. The device

is then ready for the next operation. See Toggle Bit Timing Diagram.

Product Identification

The product ID operation outputs the manufacturer code and device code. The programming

equipment automatically matches the device with its proper erase and programming algorithms.

The manufacturer and device codes can be accessed through software or by hardware operation. In

the software access mode, a six-byte command sequence can be used to access the product ID. A

read from address "00000 hex" outputs the manufacturer code "DA hex." A read from address "00001

hex" outputs the device code "45 hex." The product ID operation can be terminated by a three-byte

command sequence.

In the hardware access mode, access to the product ID is activated by forcing CE and OE low, WE

high, and raising A9 to 12 volts.

TABLE OF OPERATING MODES

Operating Mode Selection

Operating Range: 0 to 70

MODE

PINS

CE

OE

WE

ADDRESS

DQ.

Read

Dout

Write

Din

Standby

X

X

X

High Z

Write Inhibit

X

X

X

X

X

X

Output Disable

X

X

X

High Z

5-Volt Software Chip Erase

Product ID

Manufacturer Code DA

(Hex)

Device Code

45 (Hex)