PDP-11 Architecture - Memory - Data Formats

Data Formats

Sixteen-bit words were stored little-endian (with least significant bytes first). Due to the popularity of the PDP-11, this format is still sometimes referred to as pdp-endian. Thirty-two-bit data—supported as extensions to the basic architecture, e.g., floating point in the FPU Instruction Set, double-words in the Extended Instruction Set or long data in the Commercial Instruction Set—was stored in more than one format, including an unusual middle-endian format.