Data Format Conventions for PDP-11/40

This document outlines proposed data format conventions for the PDP-11/40 system, noting that while the system must remain partially compatible with PDP-11/20 software, the new conventions are designed to better align with broader computer industry standards and human intuition. Key areas addressed include:

• Bit and Byte Numbering: Retaining the established PDP-11 family numbering for hardware compatibility.
• Multiple Word Integers: Proposing that highest-order bits are stored first in memory (at location n) for improved external representation.
• Floating Point Numbers: Suggesting a natural ordering sequence for mantissa and exponent components.

The memo argues that these changes make test instructions easier to implement and align the system with global computing practices.