Name:	N 80 Z
Type:	80 column card (videx compatible)

Short description:
	For Apple ][+ only. Goes usually into slot 3. Switching to
	graphics (or 40 column text) is done via softswitch.

Installation:
	The N 80 Z fits into any slot (except 0 and 7). Slot 3 is
	recommended for Pascal and CP/M.
	It has a 14 pin IC-socket, which needs to be plugged between
	IC F 14 (74LS259) on the main board and its socket:
		Remove IC F 14, located left near the color trim poti, plug
		N 80 Z socket into the motherboard socket and then put
		IC F 14 back on the top into the N 80 Z socket.
	The male BNC connector goes into the Apple's video out connector
	and the female BNC connector goes to the monitor.

Jumper settings:
	No jumpers. Phew...

Usage:
	Simply type PR#3. The screen should switch automatically to
	80 column display.

	Key sequences:
		Ctrl-Z 0		Clear screen
		Ctrl-Z 1		Return to 40 column mode
		Ctrl-Z 3		Alternate charset
		Ctrl-Z	followed by
		Ctrl-@ to G		Lores graphic characters
		Ctrl-Z	followed by
		Ctrl-P to Ctrl-Shift-O	Line graphic characters
		Ctrl-Z 	followed by
		Ctrl-H to Ctrl-O	Abbrev. for control character
		Ctrl-A			Toggle caps lock 
		Ctrl-G			Bell
		Ctrl-H			Backspace
		Ctrl-J			Line feed
		Ctrl-K			Clear to end of page
		Ctrl-L			Clear screen
		Ctrl-M			Carriage return
		Ctrl-S			Stop/Start
		Ctrl-U			Cursor forward
		Ctrl-Y			Home (without clear)
		ESC followed by
		A to F			Like on the Apple screen
		Ctrl-Shft-M		Clear to end of line
		Ctrl-Shft-N followed by
		two characters X and Y	Set cursor to X Y; the characters
					are calculated as X+31 and Y+31

Register settings of CRT-controller:

	register r/w     normal value    Name
	00:      w       7B              Horiz. total
	01:      w       50              Horiz. displayed
	02:      w       62              Horiz. sync pos
	03:      w       29              Horiz. sync width
	04:      w       1B              Vert. total
	05:      w       08              Vert. adjust
	06:      w       18              Vert. displayed
	07:      w       19              Vert. sync pos
	08:      w       00              Interlaced
	09:      w       08              Max. scan line
	10:      w       C0              Cursor upper
	11:      w       08              Cursor lower
	12:      w       00              Startpos Hi
	13:      w       00              Startpos Lo
	14:      r/w     00              Cursor Hi
	15:      r/w     00              Cursor Lo
	16:      r       00              Lightpen Hi
	17:      r       00              Lightpen Lo

	Register is read (Slot 3 assumed):
		LDA #$<register>
		STA $C0B0
		LDA $C0B1

	Register is written:
		LDA #$<register>
		STA $C0B0
		LDA #$<value>
		STA $C0B1

The card has 2kB rom, 4kB character rom and 2kB video ram.
The rom is mapped into $CN00-$CNXFF (N is slotno) and $C800-$CBFF,
the video ram is mapped (in four banks) at $CC00-$CDFF.
Bank switching is done via accessing the addresses (slot 3 assumed)
$C0B0, $C0B4, $C0B8 and $C0BC.

Memory locations used:
	$06F8:	Screen start address (divided by 16)
	$07F8:	Status:
		Bit 0:	normal/alternate charset
		Bit 4:	18 or 24 lines
		Bit 6:	caps lock flag
		Bit 7:	GET/GETLN flag
	$C058:	Switch off card
	$C059:	Switch on card
