The Fortran H compiler was mostly written in Fortran: 27,415 lines of Fortran and 16,721 lines of assembler according to slide 12 of [1].
Thanks for the pointer. As Doug points out, Burrough's ESPOL started the transition in the early 60s, but it took awhile for it to be something that was done 100% of time by everyone. The mid-70s is clearly the transistion time - as you point out [2/3 self hosting, 1/3 assembler]. I wonder what part was which?
Wirth wrote PL/360 to create Algol-W in the late 60s. But York/APL (and I believe APL/360) which were the same timeframe, were assembler [I hacked on the former on TSS in the early/mid 70s].
The first DEC compilers for the 360 bit and 12 bit lines were written in assembler, but they switched to BLISS (and some other languages for different front-ends) by the 70s for the newer generations of compilers. Paul can give that history as he was part of it.
Clem