The Maxc Systems

The process of developing a computer system is not only inherently interesting; it also leads to significant organization concepts that the builders are often impelled to share with others. So it was in our development of the Maxc1 and Maxc2 time-sharing systems at the Xerox Palo Alto Research Center between 1971 and 1977. From this development came some ideas of system organization that are now seen to have contributed to the success of the effort:
• The high availability achieved is attributable to the simple microprogrammable organization of the machines.
• Microprogramming organization promotes simplicity by placing much of the complexity in firmware.
• This organization of a computer provides the environment for multiple instruction sets.
• Causes of failure in integrated circuitry were evenly distributed, but memory error correction was found to be important to overall reliability.
• Tools for software and firmware development and design automation are necessary for efficient development.