The information below outlines the merging  of Lego RCX ("Yellow Brick") Interfacing with MSW Logo. 

This technique is based on the work of Daniel Berger who has written dedicated routines to control the RCX. Daniel has made his C++ code available at: http://www.kyb.tuebingen.mpg.de/bu/people/berger/mindstorms.html

It is NOT based on Lego's SPIRIT.OCX, or the latest Lego SDK using GhostAPI.dll 

The approach used is to construct a DLL that interfaces with Daniel's functions and is accessible from MSW Logo using DLLLOAD and DLLCALL.

The Calling 'Chain'

The new DLL ("mswbrick.dll") has been written to sit between Daniel Berger's code and MSW Logo. MSW Logo calls mswbrick.dll which in turn accesses the functions defined in rcx.cpp This chain is necessary because MSW logo can not call rcx.cpp directly.

It should be noted that all commands are in "immediate" mode. The brick is under the direct control of MSW Logo at all times. If it moves out of range of the Tower you will lose control of the brick. If the motors are on, for example, they will stay on!

It was several hours before I realised what was wrong. I had to download the Firmware for the DLL to work!!

 
After removing the batteries from the RCX, remember to download the Firmware again.

ALSO ...
When using the USB Tower you must first install the Tower using the Lego installation disk. The DLL will not function unless the USB Tower drivers are installed first.