The Web Site to Remember National Semiconductor's Series 32000 Family


Unfortunately there are not many documents available in electronic form. The reason is that the Series 32000 family was born long before the WWW was invented. But anyway here is what I have. Any other documents are welcome!


Eleven datasheets are available. The first two are very helpful in understanding the latest implementation of the architecture. The datasheet about the NS32C032 CPU is astonishing because it was published in November 1995, ten years after the CPU was released. In 1995 the NS32C032 was completly outdated. Why this was done remains mysterious.

NS32532 CPU Datasheet

NS32381 FPU Datasheet

NS32C032 CPU Datasheet

NS32081 FPU Datasheet

NS32181 FPU Datasheet

NS32GX32 CPU Datasheet

NS32CG16 CPU Datasheet

NS32CG160 CPU Datasheet

NS32FX16 CPU Datasheet

NS32FX161 CPU Datasheet

NS32AM16x CPU Datasheet

Instruction Set

The most important document if you want to program a Series 32000 processor! Based on the original NS32000 Instruction Set Manual from National Semiconductor this version is updated to the architecture of the NS32532 CPU and NS32381 FPU.

Instruction Set Manual , released 20 October 2014

The following document describes the execution times of all opcodes of the NS32016 CPU and NS32081 FPU. It is interesting to see how many clock cycles were needed for certain operations.

NS32016 Instruction Execution Time

Application Notes

Every vendor of semiconductor devices offers Application Notes for his products. The only purpose is to support the customer. Therefore the Application Notes covers a wide range of topics from basic hardware functional descriptions to sophisticated software examples.

AN-383 : Interfacing the NS32081 as a Floating-Point Peripheral , for example to the Motorola 68000 microprocessor

AN-449 : A Systems-Oriented Microprocessor Bus

AN-464 : Effects of NS32082 Memory Management Unit on Processor Through Put

AN-540 : A Dual Access NS32532 Error Detection and Correcting Memory System

AN-543 : Interfacing the DP8420A/21A/22A to the National Semiconductor NS32332

AN-587 : C in Embedded Systems and the Microcontroller World

AN-590 : Application Development Using Multiple Programming Languages

AN-591 : Byte-Order Issues for the NS32532

AN-611 : Bresenham's Line Algorithm Implemented for the NS32GX32

AN-632 : Embedded Control Design with the NS32CG16

AN-634 : BITBLT Examples: NS32CG16 and NS32FX16

AN-695 : Digital Filtering with NS32GX320

AN-697 : Description of the NS32GX320 Bus Fairness Mechanism

AN-720 : Overflow Conditions in CMACD Instruction Execution on NS32GX320

Application Brief

An Application Brief is a short Application Note. For example the content of AB-40 fits on one page.

AB-40 : PC Board Layout for Floating-Point Units


All but one Series 32000 devices had bugs. The lone exception was the NS32382 MMU. Bugs are no surprise since all chips are complex designs. But with all the problems described in the bug sheets one may wonder that the systems build with this chips were still functional. My own experience with the NS32016 and the NS32532 CPUs is positive. I never hit a bug. But one of my NS32381 FPUs failed. I thought that it was broken but later I learned that revision C/10 had a serious bug. I replaced the FPU with a revision D/10 chip and everything was fine.

Series 32000 Bug Sheets

Richard had some earlier bug sheets on paper. They are now available as a pdf document:

Series 32000 Bug Sheets, Part 2

There is an interesting note about the NS32332 CPU revisions B and C: the interior of the NS32332 package contains Beryllium Oxide! This substance may pose a health hazard when inhaled. It was recommended that the NS32332 be returned to National Semiconductor for disposal. In the newer bug sheets this note is no longer found.

The following document is obviously not downloadable. But it is a nice book and it contains some general thoughts about designing an architecture and describes some goals of the Series 32000 designer. You can still buy it on e-bay. I got my copy in 2012. The content is based on the second generation of the Series 32000 chips. The chip on the cover is the NS32332 CPU. If you can get it for some Euros you make no mistake.

Fig. 1. To my knowledge one of two books about the Series 32000.

This chapter was last modified on 2 October 2016. Next chapter: Die Photos