What kind of apparatus could this be?
May be an old plc programmer. The text of the three positions of the key may help to discover. Also the identification of the sub-D connectors. Could you tell us? 


It seems to be a PLC programmer from the age of no-pc-at-home.
The PLCs had very little RAM (a few Kbs) and only proprietary interfaces. I have never seen a programmer that big, just handheld devices. 
In fact, nowadays Siemens programmers are pc-based devices but still called suitcases.