Volex TTX2000 S Issue 1.2: Routine at 0ADC

0ADC: set_character_pointer: Set character_pointer to start of current row in page display buffer.

Used by the routine at decode_row.
set_character_pointer	0ADC	LD DE,(page_display_buffer_pointer)	Load page_display_buffer_pointer into DE.
	0AE0	LD A,(row_number)	If row_number is zero, jump to set_character_pointer_0.
	0AE3	AND A
	0AE4	JR Z,set_character_pointer_0
	0AE6	LD B,A	Else multiply row number by 40 and add to address in DE to get address of first character of row.
	0AE7	ADD A,A
	0AE8	ADD A,A
	0AE9	ADD A,B
	0AEA	LD L,A
	0AEB	LD H,$00
	0AED	ADD HL,HL
	0AEE	ADD HL,HL
	0AEF	ADD HL,HL
	0AF0	ADD HL,DE
	0AF1	LD (character_pointer),HL	Store address in character_pointer and return.
	0AF4	RET	Store address in character_pointer and return.
set_character_pointer_0	0AF5	LD (character_pointer),DE	Store DE in character_pointer and return.
	0AF9	RET	Store DE in character_pointer and return.