8

Preliminary

CAT35C704

Doc. No. 25045-00 2/98

DEVICE OPERATION

INSTRUCTIONS

The CAT35C704 instruction set includes 19 instruc-

tions.

Six instructions are related to security or write protec-

tion:

DISAC

Disable Access

ENAC

Enable Access

MACC

Modify Access Code

OVMPR

Override Memory Pointer Register

RMPR

Read Memory Pointer Register

WMPR

Write Memory Pointer Register

Six instructions are READ/WRITE/ERASE instructions:

ERAL

Clear All Locations

ERASE

Clear Memory Locations

READ

Read Memory

RSEQ

Read Sequentially

WRAL

Write All

WRITE

Write memory

Note: All write instructions will automatically perform a clear before

writing data.

Seven instructions are used as control and status func-

tions:

DISBSY

Disable Busy

ENBSY

Enable Busy

EWEN

Program/Erase Enable

EWDS

Program/Erase Disable

NOP

No Operations

ORG

Select Memory Organization

RSR

Read Status Register

UNPROTECTED MODE

As shipped from the factory, the CAT35C704 is in the

unprotected mode. The access code length is set to 0,

and the memory pointer is at address 00 hex. While in

or written to without an access code. A portion of the

memory may be protected from any write or clear

operation by setting the memory pointer to the appropri-

ate address via the WMPR (Write Memory Pointer

Register) instruction:

WMPR

[address]

5074 FHD F13

CS

CLK

DI

HIGH-Z

DO

OP7

AN

OP0

A0

tSV

tEW

OP CODE

ADDRESS

DON’T CARE

BUSY

READY

Figure 10. Erase Timing

5074 FHD F12

CS

CLK

DI

HIGH-Z

DO

OP7

OP0

OP CODE

Figure 9. EWEN/EWDS Timing