[GreenKeys] What the Hal is it?

[Keith Densmore]

Hi All,
Just picked up a Hal ST-6 and a companion piece I have not been able to ID. 
The extra unit  is a Hal product in exactly the same case as the ST 6 with 
the same meter. It seems to have functions to change i/o speeds and some 
kind of a memory buffer. It has no data plate or model no attached.
Anyone know what it is and/or be able to direct me to some service/operating 
info?
I can provide a pix if my description needs clarification.

Thanks, 73,
Keith ve3ts