Gelip, hi!

"Обучающая программа" uses i8253 to play music between parts. You can use it to test sound. And, of course, all tape games use i8253, when you see flashing message "Остановите ленту, нажмите клавижу "ВВОД". On original spectrum you'll se only flashing border instead of sound. And this, classic tune in program "Художник" (art-studio). Here it is: http://zxbyte.ru/video/lambada.flv

And it is known that native BYTE test software "Наладочная программа" makes comprehensive tests of i8253. But we don't want to publish it...