I still have my waften IV fortran textbook.
I used fortran based software and fortran to write tools until my sgi o2 crapped out in 2014. one of the great things about fortran was that you could move subroutines around and change goto logic, recompile and get faster running code. The great thing about the hz100 was that heathkit built it as a kit and you could find ways to improve it in the heathkit magazine. I discovered ramdrive, added more memory and used ramdrive to speed thing up in both compile and execution.