Initial Feedback on Chapter Scheme, VAS MEMO #2

This interoffice memorandum, dated March 21, 1974, from Craig Mudge to the 11 Engineering distribution list, provides feedback regarding the "Chapter Scheme" for a system described as "VAS." The document outlines technical problems, suggestions, and clarifications concerning memory addressing, tagged stack implementation, and register operations. Key topics include:

• Problems: Challenges with representing a process's loaded image for swapping, specifically regarding tagged stacks and the need for the system to recognize indirect references to the stack.
• Suggestions: Proposals to use bit 0 as a tag for stack entries and indirect addresses, and to make "mode 5" more functional.
• Clarifications: Definitions for how index mode interacts with stack entries and specific rules for handling 32-bit addresses in registers during "Memory to Register," "Stack to Register," and "Register to Register" operations.