I believe the original Turbo Pascal was written in ASM by Anders Hejlsberg as that was the state of the art at the time [0][1]. Also it had been ported to various CP/M and non-x86 machines prior to becoming an x86 port. Later versions (4-7) were rewritten, most likely in Turbo/Borland Pascal or Borland/Turbo C/C++ as they relied heavily on Turbo Vision.

[0] https://en.wikipedia.org/wiki/Turbo_Pascal#CP.2FM_and_DOS_ve...

[1] http://wiki.c2.com/?TurboPascal