MaxCoderz

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rst $28
.db $0A,$45	;$450A aka _puts

$28:
jp 2810

;hl = pointer to text label

$2810:
 push hl	;sp -2
 push hl	;-4
 push hl	;-6
 push af	;-8	save af
 push bc 	;-10	save bc
 push de	;-12	save de
 push hl	;-14	save hl
 ld hl,000f	;15
 add hl,sp
;stack starts at $FFFF and counts down, so this is like:
;sub sp,15

 ld d,(hl)	;hl points to the upper byte of (pc) address that was pushed onto the stack with our reset call
 dec hl		;move to lower byte
 ld e,(hl)	;
 inc de		;skip over the address of the bcall
 inc de		;de now points to the code just after bcall(_puts)
 ld (hl),e	;essentially change our return address to just after the bcall
 inc hl
 ld (hl),d

 in a,($06)
 ld c,a

 dec hl
 dec hl
 dec hl		;points LSB of first push hl
 ld (hl),a	;replace with value of in a,($06)
 dec hl
 ld (hl),$28
 dec hl
 ld (hl),$e7	;change 2nd push hl to 28e7 location

 dec de
 ld a,(de)
 ld h,a		;MSB of our bcall ($45)
 dec de
 ld a,(de)
 ld l,a		;LSB of our bcall ($0A)
;hl = pointer to bcall

 ld b,0		;bc = whatever in a,($06) means

 bit 7,h	;bit 7 is not on
 jr nz,$2846	;if it is on, reset it

 bit 6,h	;bit 7 is off, check if bit 6 is on/off
 jr z,$284c	:if it is off, do something. else reset it

$2840:
 res 6,h
 ld a,$1b	;27
 jr $2857

$2846:
 res 7,h
 ld a,$1f	;31
 jr $2857

$284c:
 in a,($06)
 and $1f	;make sure not >31 cause below has 32  bytes
 ld de,$8230	;ti83p.inc defines this as "baseAppBrTab"
 add a,e	;add the offset
 ld e,a
 ld a,(de)	;store value at offset to a
 ld b,a		;store into b
$2857:		;bit 7 or 6 was reset, or both are already reset
 out ($06),a	;output whatever those values mean
 ld de,$4000
 add hl,de	;why do we do this? we reset bit 6 then effectively add it right back
 ld e,l
 ld d,h		;load bcall location into de
 ld hl,$0008
 add hl,sp	;point to the stack position of 3rd push hl
 ld a,(de)	;load LSB from the location pointed to at bcall
 ld (hl),a	;store it in stack
 inc de
 inc hl
 ld a,(de)
 ld (hl),a	;load from the LUT and store where it points to into stack

 inc de		;again not sure what the purpose of this is
 ld a,b
 or a
 jr z,$2874
 ld a,(de)
 neg
 add a,b
 jr $2879
$2874:
 or a
 jr nz,$2879
 ld a,c
$2879:
 out ($06),a	;this seems to do something to the bcall lookup table?
 pop hl		;recall all our values (these should be unchanged by all the stack manipulation)
 pop de
 pop bc
 pop af
 ret		;jump to bcall