When I started actually getting paid to be a computer geek, I started as a system administrator/database administrator on Sperry/ Unisys 5000 mini-computers. These were about the size of a small refrigerator, and were designed for mostly serial I/O with dozens up to hundreds of serial ports in the back. They were based on 40 MHz 68040 CPUs and ran a proprietary port of ATT System V Unix. We used Oracle version 6.0.36 (and later Oracle 7) on them with our own proprietary character based financial, logistical, and personnel applications. If you want to see what one of those looked like, enter the U5000 Memorial.