The AMD AM9511 Arithmetic Processing Unit, first produced in the late 1970s, provides hardware support for high performance fixed and floating point arithmetic and a variety of floating point trigonometric and mathematical operations, for use with microprocessors of that period.
This repository provides schematics and board design for a module that can be connected to the 6502 bus interface, allowing the AM9511 to be addressed as an I/O device in a 6502-based microcomputer.
This project was made possible, in part, by the generous sponsorship of PCBWay, who provided fabrication services in exchange for promotional consideration. Please see my review of the service provided by PCBWay, and consider their services for your own projects.
The design is adapted from the work of Kissel and Currie[1] in which they developed an experiment using a MOS 6502 microprocessor to control four AM9511A floating-point arithmetic units, and from Hart’s MICROCRUNCH[2] which also used the AM9511A (Intel 8231A) interfaced with a (Rockwell) 6502.
See am9511-6502-description.pdf for a full description of the interface circuit design and am9511-6502-schematic.pdf for the schematic.
The specification here anticipates the use of an AM9511A clocked at 4 MHz. However, the same design will work with earlier versions of the AM9511, by swapping the 4 MHz clock oscillator with a unit of an appropriately lower speed.
The logic folder contains the programming details for the ATF16V8B
used in the circuit, as produced by Galette
from the am9511-logic.pld source file. The provided JEDEC file
(am9511-logic.jed) can be easily programmed into an ATF16V8B using
minipro.
Also included in the docs folder are source documents cited below, as
well as datasheets and supplementary documents for the AM9511.
This repository contains the full KiCad sources for the schematic and a PCB design for the module. The PCB is designed in prototype form with a pin header suitable for connecting the module to a breadboard using Dupont type male-to-female ribbon cable.
- Kissel, R and Currie, J: "Hardware Math for the 6502 Microprocessor"; July 1985; NASA TM-86517
- Hart, J: "MICROCRUNCH: An Ultra-Fast Arithmetic Computing System (part 1)"; August 1981; MICRO - the 6502/6809 Journal (No. 39)