Shows how Atari Basic can be copied from ROM to RAM... Credits: https://goto10.substack.com/p/change-the-atari-basic-ready-prompt. This is my version of the code from the link mentioned.

AtariBasicPatcher.asm

; Copys Basic from ROM into RAM. 
;
; Allows one to change Atari Basic, e.g. change ready prompt etc.
;
; Initial idea: https://goto10.substack.com/p/change-the-atari-basic-ready-prompt
;
; B.Fritz 10/2022
; ---------------------------------------------------------------------------------
; Some addresses to play with:
; 	Ready promt starts at: 48499
;
	org $0600

	lda #0
	sta 204
	lda #160	    ; Basic starts here => 40960
	sta 205
	
	ldy #0
	ldx #32		    ; 32 pages => 8192 bytes.
loop
	lda (204),y   ; This does the trick: Copy one byte from ROM to the same addrress in RAM
	pha			      ; Get byte from ROM
	lda #255	    ; Basic off
	sta $d301
	pla			      ; Write back to RAM
	sta (204),y
	lda #253	    ; Basic on
	sta $d301
	iny
	bne loop
	inc 205
	dex
	bne loop	    ; Repeat until all 32 pages are done.
;
; Example on how to change Atari Basic in RAM
;
	lda #255	    ; Basic off
	sta $d301

	ldy #0		    ; Change prompt.
	ldx #5
l2
	lda prompt,y
	sta 48498,x
	iny
	dex
	bne l2
;
; Activates Basic rom and returns.... 
; To activate in- ram- basic type Poke 54017,255. 
; To return to in- rom- version type Poke 54017,253
;
	rts	
;
; Some Data
;
prompt
    .byte 'Ok     '

Switching between Atari Basic in ROM and its customized version in RAM....