I haven't bothered to download 6.4.3, but the following is true for all versions of Knoppix that I have use. Cheat codes are entered at the boot prompt as soon as Knoppix starts booting, long before you hear the startup message. You have to enter something fast to prevent the time-out and booting to continue, the best thing for me is to tap F2 and/or F3, which will stop the boot from continuing automatically and also give you some help. Also be advised that for most cheat codes you need to type in the name of the kernel first. For example enter knoppix toram rather than just toram. And this is Linux, so case is important.