This, but (or "and") use the 4-row layout that dozens of tracker programs used[0], to fit over 2 octaves on the computer keyboard.
On a US keyboard:
QWERTYUIOP[] is the white keys starting at middle C. (The row above is the black keys; the 2 key plays C#.)
ZXCVBNM,./ is the white keys starting an octave lower. (S plays a low C#.)
The two ranges overlap; e.g. Q and , both play C in the same octave.
Grew up composing music on a computer this way when my (musical) keyboard didn't have MIDI and I couldn't afford a better one :)