On 6502-based computers, C was highly unusual. Not only was C not nearly that widespread in hobbyist computing, but it's really painful on an 8-bit CPU with such a tiny stack (256 bytes) and few registers.

Forth, on the other hand received lots of attention for its small size and compact code, and e.g. I remember articles extolling Forth as easier to learn than BASIC at the time....

It's not the runtime that's the problem but the compiler. Though there have been C compilers on 8 bitters.

I used to use a C compiler for the Z-80 called BDS C. BDS stood for "Brain-Damaged Software" because it didn't implement floating-point.

Until the early 1980's, C was highly unusual.

Definitely not unique - if you've ever seen the code size you can get a Forth interpreter down to, you'd know why it might've been tempting.

There were actually a few of the more obscure systems of that era choosing it - albeit fairly horrific for a beginner to learn compared to BASIC. Some of the Z80-based CP/M ones, for example (the daughterboard in the… um, repurposed?… Torch I had as a child, although what I actually used was the BBC part of it, because come on, BBC BASIC with a built-in 6502 asm!), or the ZX81-style Jupiter Ace.

Not unique, old.

Remember these?

http://en.wikipedia.org/wiki/Jupiter_Ace

I used to see them on the advertisements section of the Spectrum magazines I used to buy.

Back in the home computer days, no one cared for C, it was all about Assembly, Forth and BASIC.

On the home computers powerful enough to run CP/M, C was just yet another language (mostly a subset of the UNIX one).