FPF11 Floating-Point Processor Technical Manual

This document, the "FPF11 Floating-Point Processor Technical Manual" (EK-FPF11-TM-001) published by Digital Equipment Corporation in July 1981, provides a detailed technical description and service information for the FPF11.

The FPF11 is a hardware option designed to enhance PDP-11/23 and compatible central processing units (CPUs) by executing floating-point arithmetic operations. Key features include:

• High Performance: Accelerates floating-point operations through a dedicated high-speed 64-bit data path and an internal clock for variable-length microcycles.
• Architecture: Contains six 64-bit floating-point accumulators (AC0-AC5), scratch-pad registers, and status/error registers. It operates with both 32-bit (single-precision) and 64-bit (double-precision) data modes.
• Integration: Installs as a quad-height module (M8188) connected to the CPU via a ribbon cable, without affecting system bus loading.
• Compatibility: Uses existing PDP-11 addressing modes and memory management.
• Data Handling: Recognizes short/long integer and single/double precision floating-point formats, and handles conversions between these types during load and store instructions.

The manual is structured into seven chapters:

1. Introduction: Covers the FPF11's general features, architecture, specifications, and related documents.
2. Review of Floating-Point Numbers: Outlines the fundamentals of floating-point arithmetic for background understanding.
3. Data Formats: Details the integer and floating-point data formats used by the FPF11, including the Program Status Register and processing of floating-point exceptions (e.g., overflow, underflow, divide by zero).
4. Floating-Point Instructions: Describes the FPF11's comprehensive instruction set, including arithmetic, data movement, conversion, and status control instructions.
5. Functional Description: Provides an in-depth look at the FPF11's internal control and data flow, including its microcontroller, MIB and DAL interfaces, and microprocessor data path.
6. Inspection and Installation: Offers procedures for inspecting the module and installing it in compatible PDP-11 systems, including jumper configurations.
7. Maintenance: Lists diagnostic programs (MAINDEC CJFPAA and CJFPBA) used to validate and troubleshoot the FPF11.