Actually, the original ASCII proposal did include an up arrow and a left arrow. The final version a few years later replaced these with ^ and _ respectively. So

Actually, the original ASCII proposal did include an up arrow and a left arrow. The final version a few years later replaced these with ^ and _ respectively. Some companies adopted the original ASCII. When Smalltalk-80 was developed it replaced its own quirky character set with ASCII but used the up arrow to indicate return and left arrow assignment. This made Squeak Smalltalk code look wrong, like "x _ x + 1", depending on the font you used and some people wanted to allow underscores in identifiers to make it easier to interface to other languages. So "x := x + 1" was added as an option and there have been some crusades to convert all older code to that.