speaking of Intel computers - ARPA DOT?

I was out scrounging yesterday and found an odd looking computer (I THINK it was a computer) with a name plate that said ARPA DOT. Any idea what this is? It was heavy aluminium case about two foot high and about 8 inches wide and about 2 foot deep. The top edges were cut at 45d angle about 1" high and the bottom flared out about 1 1/2" on each side and the case was painted a dark grey. On the bottom front was a brass name plate that was screwed to the case. The name plate said ISSI Intel ARPA DOT and was arranged like this: ARPA ISSI Intel DOT The case had two large vertical card solts that opened in the front. The one on the left had a 3 1/2" hard drive in it. The one on the right was emply but looked like it held the CPU, memory etc. There didn't appear to be any electonics in the case except for the power supply. The "drive board" had a small HD SCSI connector on the front but there were no other connectors on the outside the case except for one for an AC power cord. It was definitely unique looking but since the main board was missing and I had a full load I passed it up. I TRY to keep my digital camera with me for opportunities like this but I was driving a different car and didn't have it. Joe