The Turbo Pascal version of this was even better, because you could do a whole block of asm instead of just a single line at a time. As I remember there were annoying limitations in the C version around labels and such. It was incredibly useful when writing performance oriented code at that time because it was very easy to write code that would outperform the compiler.

I'm pretty sure you could do asm blocks in Turbo C using brackets, e.g. asm { ... }, though it might have been a Turbo C++ thing (i never really used plain TC much).