FP11-A Floating-Point Processor User's Guide

This document is a User's Guide for the FP11-A Floating-Point Processor (EK-FP11A-UG-001), published by Digital Equipment Corporation in May 1978.

The guide describes the FP11-A, a hardware option designed to enable the PDP-11/34A central processor to execute floating-point arithmetic operations efficiently. Key aspects covered include:

• Functionality: It performs all floating-point arithmetic and converts data between integer and floating-point formats, offering a speedier alternative to software routines. It supports both single- (32-bit) and double-precision (64-bit) data modes, with 17-decimal digit accuracy.
• Architecture: The FP11-A includes its own microprogrammed control store, scratchpad registers, a floating exception address pointer (FEA), status and error registers, and six 64-bit general-purpose accumulators (AC0-AC5), with AC0-AC3 used for data transfers with the CPU/memory.
• Physical Description: It consists of a single hex board (M8267) and modifications to the PDP-11/34A CPU boards.
• Data Formats: Details the integer (16-bit short, 32-bit long) and floating-point (32-bit single-precision, 64-bit double-precision) data representations, including sign, exponent (excess 200 notation), and fraction. It also explains the FP11-A Program Status Register and handling of floating-point exceptions.
• Instruction Set: Provides a comprehensive overview of the FP11-A's floating-point instructions, covering arithmetic operations (add, subtract, multiply, divide), load, store, convert instructions (between integer/float and single/double precision), and instructions for managing processor status and modes.
• Installation & Maintenance: Includes procedures for installing the FP11-A and FP11-AU upgrade kit, calculating power requirements, running diagnostic tests (MAINDEC DFFPAA, DFFPBA, DFFPCA), and utilizing the programmer's console for troubleshooting.
• Processor Organization: Explains the internal hardware, including the AM2901 microprocessor, RAM, ALU, and control logic.

In essence, the document serves as a comprehensive manual for understanding, installing, programming, and maintaining the FP11-A Floating-Point Processor for the PDP-11/34A system.