After abacus, mechanical calculator, then TI, HP, then Wang. Those were the good old days.They were manually enter trading data in charts during the day. They hired lots of clerks to do that. The quotes in the trading pits were manually given to clerks who use the erasure to make changes in price.
literally the charts were manually drawn by hand
and the guy read the ticker tape manually.
people prior to the 70's were doing taxes with pen and paper and abacus calculations on paper and no calculators.
A good friend, who traded options in the 70s, said it was much easier to make money on options then if you knew some maths and understood arbitrage.