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ROM Used by Different Microprocessing Units

IP.com Disclosure Number: IPCOM000060869D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Inui, T: AUTHOR [+3]

Abstract

This article describes a method of using a ROM (read-only memory) of the same type in a different MPU having a different programming language. It was impossible to use the same ROMs in different MPUs because each MPU had its own programming language and it could not be started by the same MPU. And when the machine had different MPUs, the program had to be written by different languages. However, if the difference between programs in different MPUs exists in program start addresses, it is possible to use ROMs of identical type commonly for loading programs for MPUs of different kinds. This procedure requires that those programs have different program start addresses or different initial instructions from each other.

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ROM Used by Different Microprocessing Units

This article describes a method of using a ROM (read-only memory) of the same type in a different MPU having a different programming language. It was impossible to use the same ROMs in different MPUs because each MPU had its own programming language and it could not be started by the same MPU. And when the machine had different MPUs, the program had to be written by different languages. However, if the difference between programs in different MPUs exists in program start addresses, it is possible to use ROMs of identical type commonly for loading programs for MPUs of different kinds. This procedure requires that those programs have different program start addresses or different initial instructions from each other. This difference in start addresses or initial instructions, where programs start at or after program reset, is utilized to make the distinction between different programs stored in a ROM. This method may be implemented as follows for MPUs 8085 (start address is 0000), and 6800 (start address is stored in X'FFFE', X'FFFF'): 1. Program starts for address "0000" in MPU 8085. 2. Program from address "0000" by 8085 assembly language. 3. Set starts address at "FFFF" in MPU 6800. 4. Program from start address by 6800 assembly language. Some examples in other cases are: 1. 8080, 8085 and Z80 use the same start addresses "0000". So, this method can not be used unless a flag bit is used to divide a ROM for each program...