Browse Prior Art Database

CHECKSUM FOR ON CHIP MICROCODE RAM APPLICATIONS

IP.com Disclosure Number: IPCOM000009090D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-07
Document File: 2 page(s) / 87K

Publishing Venue

Motorola

Related People

Jehoda Refaeli: AUTHOR [+3]

Abstract

This paper describes improvements in Random Access Memories (RAM).

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At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 57% of the total text.

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MOloRoLA Technical Developments

CHECKSUM FOR ON CHIP MICROCODE RAM APPLICATIONS

by Jehoda Refaeli, E. David Bell and Gil Pate1

INTRODUCTION

This paper describes improvements in Random Access Memories (RAM).

PROBLEM

  In some applications, a RAM (10) is used for read-only purposes. For example, in a system with a TPU, several microcodes are loaded and executed depending on parameters. Similarly, a communica- tion processor simultaneously operating substantial- ly different algorithms. In these applications avail- able RAM bandwidth is restricted such that the dam
(14) bus has limited RAM access.

  In a noisy environment, electromagnetic inter- ference (EMI) could corrupt the microcode stored in the RAM thereby causing the host (12) to operate incorrectly. Especially in automotive applications, the reliability of TPU microcode is of paramount importance because of the safety implications.

SOLUTION

Immediately after loading the microcode into the RAM (lo), the initialized application (host

interface 12) reads the microcode. An independent circuit (20) is provided with a counter (22), a check- sum register (24) (e.g., 32 bit) and a state machine
(26). The circuit (20) repeatedly scans the RAM Array(l0) from the highest to the lowest addresses. For each RAM address the circuit (10) calculates a specific checksum based on the data from the cur- rent address and the checksum from the previous RAM address. At the end of each cycle (e.g., at address zero), RAM array checksum...