Comment by StillBored

Maybe everyone needs their ansi.sys moment though. Back in the early 1990's, I, and probably half the programmers using DOS, rewrote the dos ansi.sys driver/TSR because its was _SLOW_. mostly IIRC because it was calling the BIOS text output, but also because it was a pretty solid implementation of the ANSI terminal/esc sequence "standard".

So, the first half took about an hour or two to handle output (just write a character at the right location in the framebuffer) and get the INT/TSR boilerplate right. Then for the next 20 hours fight with all the edge cases the cropped up with corrupted text in various TUI programs that were calling the DOS string functions. Then as the size+perf approached NANSI.sys (http://www.kegel.com/nansi/) give up...

Learning experience.