Four chords progression

Key is E minor ie all notes natural except F which is black key or #F.


Using Bach bass code:


G6 ie G B E
B ie B D B or D F B etc (remember F is #F)
D6 ie B D B or D F B
A9 ie C E B (the 3rd wrt bass taken too, Bach Bass Rules)


So it is based on B pedal or sustained at the right hand or a high part.


a simple melody that could go with...


G . . F E . F G . . . . . . . .
F . . E D . E F . . . . . . . .
same
E . . D G . . F E . . . . . .


Later addition:


Harmony that can go this is shown evolving at:
https://euroelectron.blogspot.com/2019/09/on-prepared-pair-of-dissonant-notes-to.html


Bass can be G B E-------- (E at first beat of bar), similarly below
F A B--------
A D F---------
G B A -------


Other melodies added such as:


E F G B
B C A GA
-------- (sustained A)
A B G FG
----------(sustained G) G A F EF


Remembering all F are F sharp


Musical composition can evolve as a Bolero - Ravel like composition, or Canon in D - Pachebel with parts continuously being added while previous played ones repeat in a loop.


For example violins at 1/16ths starting at a high G going to E a minor 3rd below it.


GEGEGEGEGEGEGEGEGR
FEFEFDFDFDFDFDFD...
FDFDFDFDFDFD..
EFEFECECECEC









Reference :


Bach Bass Rules - Bach, Niedt - PDF