.Page
;++
;
;		New PreNibble routine
;	This routine will create 5 bytes ( 4 from the 524 byte i/o buffer and
;	one from the checksum ) and will save them in the zero page for use
;	during the writing operation.  It is a brute force operation, reading
;	will call a routine that will combine theh top 2 bits of each into
;	one byte that is returned within the 'A' register.
;
;	Buffer[1] == >AAAAAAAA<
;	Buffer[2] == >BBBBBBBB<
;	Buffer[3] == >CCCCCCCC<
;	Result :=  Nibl[00AABBCC]
;--
;
;	REGISTERS
;		ALL == DESTROYED
;
;	Local Equates
;--

C1BTo1	.Equ 02FF
C1BTo2	.Equ 0300
C1BTo3	.Equ 0301

C2BTo1	.Equ 03FE
C2bTo2	.Equ 03FF

;++
;	Global Equates
;		CkSum1
;		CkSum2
;		CkSum3
;		CpCkSum
;		CpBy01
;		CpBy02
;--
.Page
PreNib	.Equ *				; Entry point for all callers
	Ldy	C1BTo1
	Ldx	C1BTo2
	Lda	C1BTo3
	Jsr	Fr3To1
	Sta	CpBy01			; Save the new composite byte

	Ldy	C2BTo1
	Ldx	C2BTo2
	Lda	#00			; Only two bytes in this one
	Jsr	FrTo1
	Sta	CpBy02			; Save the new composite byte

	Ldy	CkSum1
	Ldx	CkSum2
	Lda	CkSum3
	Jsr	Fr3To1
	Sta	CpCkSum
	Rts				; Back to the caller