Rigol DS2000 micro-bug:
1) If you scroll through Type on the Trigger Menu, you will see that three triggers (Pattern, Delay, Duration) cause the sample frequency to be cut in half (like turning on a second channel). This - by itself - may
not be a bug - since those triggers
can use a second channel as source (although they don't have to), so perhaps Rigol prepares the sample speed for two-channels. Anyway, select one of these triggers (e.g. in the images, I selected Pattern).
2) Go to Acquire Menu and select MemDepth -> 7kPoints.
3) Go back to Trigger Menu and select Type -> Edge.
4) Go back to Acquire Menu and select MemDepth -> an Easter Egg appears on the menu.
5) Select the Egg.