I'm 44, and started programming when I was 12 on a ZX81 and then a Commodore64. Back then we had magazines instead of the internet, and any serious program was written in assembly rather than BASIC. One of the more advanced things the magazines did was print out hex dumps of the machine code, with a checksum on each line, and there was a program (which you had to enter manually) that would let you type in those hex dumps. It would checksum each line as you went along and warn you if the checksum you entered didn't match the checksum of the bytes you entered. That was a huge improvement over just typing in the programs, because you knew you didn't have any typos.

Many, many hours were spent typing those programs in. I'm still really good at typing with one hand while the other is used to point at what I'm typing in.