There is an interview with Don Knuth somewhere where he talks about having to work in numerous low level languages simultaneously to write compilers for differe

There is an interview with Don Knuth somewhere where he talks about having to work in numerous low level languages simultaneously to write compilers for different machines in the 1960s. He added that learning MIXAL/MMIX is no big deal compared to the days when every computer had a different architecture you had to learn, sometimes with little documentation.