Browse Prior Art Database

FLEXIBLE METHOD FOR CODE ENHANCEMENT OF MASKED PROCESSOR DEVICES

IP.com Disclosure Number: IPCOM000008711D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-04
Document File: 2 page(s) / 110K

Publishing Venue

Motorola

Related People

Horst Geib: AUTHOR [+2]

Abstract

Currently, there are many applications for microcomputer based systems. Consequently, the microcomputer market has significantly developed requiring more flexible and cheaper devices. The major driving factor in lower product prices is for the software to be flexible and easily expandable in order to enhance product features or incorporate completely new behaviors. Furthermore, the users request increased functionality or features sets and more comfortable handling and product usage. This leads to a struggle between development costs and complexity of a product. It is very important for the success of a product to match the market needs for the suitable product feature set at the right point of time.

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MOTOROLA Technical Developments

FLEXIBLE METHOD FOR CODE ENHANCEMENT OF MASKED PROCESSOR DEVICES

by Horst Geib and Jiirgen Schmidt

INTRODUCTION

  Currently, there are many applications for microcomputer based systems. Consequently, the microcomputer market has significantly developed requiring more flexible and cheaper devices. The major driving factor in lower product prices is for the software to be flexible and easily expandable in order to enhance product features or incorporate completely new behaviors. Furthermore, the users request increased functionality or features sets and more comfortable handling and product usage. This leads to a struggle between development costs and complexity of a product. It is very important for the success of a product to match the market needs for the suitable product feature set at the right point of time.

  The increased complexity of the software requires the ability for updating software in existing devices. In "high tier" products, this feature can be realized by EPROM or Flash technology. Hardware architectures for "low tier" products often use a fixed masked ROM version of microprocessors. Masked processors are used because they save the cost and board space for external memory storage. In addition, masked versions can be produced in large quantities and purchased for less money than unmasked versions. This becomes the main disadvantage when addressing the above mentioned market requirements.

PROBLEM(S) TO BE SOLVED

  Once programmed into the hardware, the software cannot be changed during the lifetime of the microcomputer device. To manipulate software in such a system, the software typically contains pre-programmed, fixed checkpoints containing executable code in a non-volatile, but writeable memory, that can be accessed when required. This

executable code can be called up after specific steps in the program flow via a software interrupt routine. This interrupt routine will verify whether the non- volatile memory contains an additional piece of code to execute or not. If code is available the interrupt routine branches to the detected code and executes it. When finished, the program flow can continue with the code execution out of the masked ROM. This algorithm can be used to fix minor bugs or "cosmetic" changes or updates. The main disadvantages of this technique include:

a. the checkpoints must be determined during software development;

b. unwanted additional processor...