Ah, yes... That editor is infamous among those of us who can't read Moonspeak.
If your replacement layout takes up more space than the original, the Editor freaks out and refuses to save. For this reason, it's actually easier to just hard-key your replacement into the ROM. Check out the last twenty lines of code, starting at $9ED0. Your first snippet is "20-A6-54-26". What that means is "Starting Point 20A6, twenty consecutive writes of Tile #26". You'll see a lot of that sort of four-byte clustering, where the first two bytes are the starting point, the third byte encodes Repetition, Direction and Number, and the final byte is the Tile ID#. (The other format involves a third byte which merely states the Number of tiles to be written in a simple horizontal line. It's followed by that same number of unique Tile ID#'s.)Starting Points
The top line of the Title screen is 2000-201F (32 tiles). The next line is 2020-203F. Etc. The very bottom line is 23A0-23BF. There is a subsequent target region from 23C0 to 23FF, which encodes Attributes. These are essentially color-swatches applied to the background, and is a topic best left for later.Repetition
If the 6th bit of Byte Three is set (4x, 5x, 6x, 7x, Cx, Dx, Ex, Fx), you've got repetition.Direction
Tiles are written horizontally unless the 7th bit of Byte Three is set (8x, 9x, Ax, Bx, Cx, Dx, Ex, Fx).Tests
1) You want to write Tile #69 at a position halfway down, and halfway across the screen (e.g., just southeast of center). What's the code?
2) You want to write Tile #69, five times in a horizontal row, starting halfway down the screen. What's the code?
3) You want to write Tile #69, nine times in a vertical column, starting a quarter-way down the screen. What's the code?
4) You want to write Tiles #69, #6A and #6B in a vertical column, starting a quarter-way down the screen. What's the code?