Used by the routine at SHOW_PLAY_AREA.

The buffer's row 0 is the bottom line of the play area, since the game's y counts upwards, so the copy starts there, at line 127 of the screen, and works up to line 16. It uses the stack: SP is pointed just past the end of a screen line, each PUSH puts two buffer bytes onto it, and eleven of them fill the 22 columns 7 to 28, while HL reads the buffer backwards. Only bytes 2 to 23 of each 24-byte buffer row are copied: the first two are a margin that sprites at the left edge are drawn into unseen (DRAW_SPRITE). Interrupts are off throughout the game, so nothing else uses the stack meanwhile. Checked in the simulator: buffer row 0 goes to line 127, row 111 to line 16, and byte 2 of a row to column 7.