'Couse sometimes I need to chech what is wrong - program, programmator, links or MCU. To check signals is a good methode I believe.
And to slow down DUDE. Some of my MCUs are dead (seemengly) but when I try to program them with VERY slow LPT Bitbang programmator - o Lord! They are alive. So I need an instrument to program my MCUs as slow as I want - DC included.