I made my own dcu3 jtag with v2.3.1 and just downloaded old v1.8.1 and v1.9.6 to work on projects that were written with those.
You need an ftp client to get in,that's why it remains invisible to regular webbrowser users.They have 2 ftp sites,1 is in europe.
Added after 6 minutes:
they also have osplus for download.
Introduction
OSPlus is an enhancement package for the OS20 and OS21 operating systems. It provides several new APIs that enable device drivers and I/O infrastructure.
How this document is organized In this manual, OSPlus functions are divided into a number of services. Each of the major service types is described separately, using a common layout:
● an overview of the service and the facilities it provides
● a list of the macros, types and functions defined by the service header file
● a detailed description of each of the functions in the service
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