Yeah, TSR was definitely the kick-ass programming technique at the time because it DOS was so limited. The only way to pep it up was to install some TSR sidekicks. Writing these TSR sidekicks was difficult if one wants it to do it correctly because there was no official way to do all the hooking stuffs. I remember I wrote a small utility to make correct statistics about my working sections even when the computer crashed. There were days with 12 resets or even more(!) when I was writing a keyboard drivers! Yeeh, it was such a good time.