FreeDCE is The Open Group's reference implementation of DCE/RPC 1.1 updated to be interoperable with free software development practices. FreeDCE is Distributed Computing Environment/Remote Procedure Calls 1.1 reworked, and it includes an up-to-date implementation of DCEThreads that actually works with the Linux 2.4 and 2.6 kernels on x86 hardware and also on AMD64 processors.
DCE/RPC was commissioned by the Open Software Foundation in a "Request for Technology". Apollo Computer brought in NCA - "Network Computing Architecture" which became Network Computing System (NCS) and then a major part of DCE/RPC itself. The naming convention for transports that can be designed (as architectural plugins) and then made available to DCE/RPC echoes these origins, e.g. ncacn_np (SMB Named Pipes transport); ncacn_tcp (DCE/RPC over TCP/IP) and ncacn_http to name a small number.
MSRPC is a Microsoft proprietary technology also derived from the Distributed Computing Environment 1.1 reference implementation, but has been copyrighted by Microsoft. MSRPC is featured in Microsoft's Distributed Component Object Model (DCOM), a proprietary technology for software components distributed across several networked computers to communicate with each other. The addition of the "D" to COM was due to extensive use of DCE/RPC. DCOM, which originally was called "Network OLE", extends Microsoft's COM, and provides the communication substrate under Microsoft's COM+ application server infrastructure. It has been deprecated in favor of Microsoft .NET. DCOM would be "donated" by Microsoft to the Open Group, an industry consortium to set vendor- and technology-neutral open standards for computing infrastructure. It was formed when X/Open merged with the Open Software Foundation in 1996. However, DCOM comes without several of application-level class libraries, such as ODBC, OLE DB, ADO, and ASP to run on top of it. Microsoft never released these specifications to the Open Group or the public.