Casio

I was still using my Casio PB-700 at that time, I really could not do without it as I had a whole bunch of very useful analysis programs running on it. I had expanded the setup in 1989 when I bought the cradle, printer and tape deck and in March 1990 it became invaluable when the PB-700 wiped itself of every program for some reason, my lug programs, hoop stress, margin calculations and of course, the very valuable "one armed bandit" program that I had honed to perfection over the years. 

It was a shock, but, when I arrived home that day I pulled out the interface, found the backup micro-cassette and restored the baby back to life.