< I had not realized that the TU-58 was normally an internal unit. The < one I picked up some years ago was an external unit. Perhaps it came < from a VAX 750 rather than a PDP-11/44 which is what I thought < I had remembered. it was available both ways. It was used in the 11/44, PDT-11/130, VAX 11/730 and 750s as internal. The unit was also available as external. < Any idea of where that "C" source code is? It might be necessary to < replace the TU-58. I forget where but it's flakey code. It was written to run on a unix box. The file I have is TU58-emu.zip. Allison