Two simple utilities for communicating with YIMP and YEXP on the HP41CL:

CLWriter.exe: send a binary file to the HP41CL.

CLReader.exe: receive a binary file from the HP41CL.

Compile these with

c:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\csc.exe /t:exe CLWriter.cs

c:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\csc.exe /t:exe CLReader.cs

Note: Adjust path to .net framework as necessary.