;**************************************************************************
;***                                                                    ***
;***                    Screen to printer DUMP                          ***
;***          Kaypro 10 Version copyright (c) 1984 Reliable Software    ***
;***            This program can be freely used and distributed for     ***
;***              Non Commercial purposes                               ***
;***       Micro Cornucopia Release 2.4    New 4 version 3/14/84        ***
;***			            2.5    Remove hard address for      ***
;***				           kbdin     DmC  5/7/84	***
;***				    2.6    Fix addressing for new       ***
;***                                       u board  (subtle bug)        ***
;***					             DmC 5/10/84        ***
;**************************************************************************
; initialize patch by copying to FF10h

	ASEG
	.z80
	org 	100h

	FALSE	equ	0000
	TRUE	equ	NOT FALSE

;************************************************************************
;*									*
;*	Set the following equate as appropriate for your system		*
;*									*
;*	New Kaypro 4 - 0F600h						*
;*	Kaypro 10    - 0EA00h						*
;*									*
	bios	equ	0EA00h		;BIOS base page			*
;*									*
;************************************************************************

conin	equ	bios + 0Ah
vidout	equ	bios + 0Ch
prntout	equ	bios + 0Fh

	ld	de,(conin)		; make sure we don't patch twice
	ld	a,d
	cp	0ffh
	jr	z,allred		; jump here if program already in MEM

	ld	de,0ff10h		; destination address
	ld	hl,code			; source address
	ld	bc,codend-0ff10h	; length of patch
	ldir

; initialize bios by changing the conin jump table entry to jump to this 
; program first to see if screen dump desired

	ld	de,(conin)
	ld	(kbdin),de
	ld	hl,entry		; this is our conin jump entry
	ld	(conin),hl		; patch into bios jump table

	ld	de,MSG			; tell user we are on line
	ld	c,9			; bdos print string function
	call	5			; calling Mr. Bdos
	ret				; takes us back to CCP control

MSG: 	db	'Screen Print On$'

allred:	ld	de,ALR			; tell user already on line
	ld	c,9			; bdos print string function
	call	5			; call Bdos Brothers

	ret				; to CCP control

ALR:	db 	'Screen Print Already On$' 	


; main body of dump code....................................................
;
; This program intercepts any bios CONIN call and replaces the return address
; with a return to here. This code tests for 1Ch ( cntrl-backslash ) from the
; keyboard and dumps the screen memory to the printer if true. Any other key
; hit is passed to the calling program by jumping to the address originally
; located at conin vector. Absolute addresses are used to prevent problems
; caused if User were to run the dumpscreen installation twice...............
  
code	equ	$

	.phase	0FF10h

entry:	db	0CDh			; call op code
kbdin:	ds	2			; get keyboard character
	cp	00h			; if ^W will dump screen
	ret	nz			; else will return normally

;**************************************************************************
;***    Now the actual screen dumping is done                           ***
;***                                                                    ***
;**************************************************************************


	ld	c,27			; remember cursor position
	call	vidout			;
	ld	c,'B'			
	call	vidout
	ld	c,'6'
	call	vidout

main:	ld	c,27			; move cursor to 0,0 (home position) 
	call	vidout
	ld	c,'='
	call	vidout
	ld	c,32			; <---: not a fixed number
row	equ	$-1			; this keeps track of row we are
	call	vidout			; dumping 
	ld	c,32
	call	vidout

; Now we find out where we are in video memory and pick up the address

	ld	a,14			; select crtc register 14
	out	(1Ch),a			; (cursor position)
	in	a,(1Dh)			; read in cursor pos H
	and	7			; not to exceed 800h
	ld	h,a
	ld	a,15			; select video register 15 (CUR pos)
	out	(1CH),a			
	in	a,(1Dh)			; read in cursor position to L
	ld	l,a
	ld	d,80			; chars/line
	call	advid

; The Kaypro model 10 and the new 4 use the 6545 intelligent video controller
; This chip contains various control registers which can be used to set
; cursor characteristics, to interface a light pen, and to load/unload data
; to video memory, Thhese Kaypros comunicate with video memory via I/O ports
; as illustrated above. Although the 6545 can address 16K of video memory
; ( actually more in special setups ) the Kaypros use 2048 bytes for storing
; the screen. The other 2K of video memory present on the Kaypro board is
; used for the storage of video attributes. The Kaypro bios contains a
; variable for storing the address of row 0, column 0. This is used to 
; calculate all cursor postioning. This variable is incremented by 80 each
; time the screen is scrolled one line. This technique allows wrapping
; around the 2K of video memory rather than assigning fixed addresses to
; every screen location.
;
;
; The 6545 allows loading/unloading of video data by accessing a dummy
; register (31). Every access of 31 causes the update address to be
; incremented by one. The first version of this program used this feature
; but characters were lost when the wrap at 800h occurred. ????????
;..........................................................................
; The next 3 instructions were commented out because the time required    :
; to complete the loop is sufficient to insure that the 6845 status will  :
; indicate ready. When using quicker loops ( such as saving the screen to :
; memory) the staus register must be polled                               :
; This version actually uncomments these lines                            :
;..........................................................................

l1:	in	a,(1Ch)			; get status
	or	a			; ready if bit 7 high
	jp	p,l1

l2:	in	a,(1Fh)			; attempt a read
	cp	20h			; everthing in video memory should 
	jp	m,l2			; be greater than 20h
	ld	c,a
	CALL	print			; this routine dumps one char to  
					; the printer
	inc	hl			; bump video address counter
	ld	a,8			; check for wrap at 800h
	cp	h
	jp	nz,nowrap		; not yet:: jump over next two inst. 

	ld	hl,00			; start over at 0
	call	advid			; set 0 as new address

nowrap:	dec	d			; now check to see if we got
	jr	z,lindon		; all characters on the line
					; if so we will do a carriage return
					; line feed
	jp	l1			; else get next character

lindon:	call	CRLF			; done with line
	ld	d,80			; char count for next line
	ld	a,(row)			; update row count
	inc	a
	ld	(row),a
	cp	57			; last row (rows begin at 32) 
	jp	nz,main			; nope do more

done:	call	CRLF			;linefeed to flush buffer
	call	prntout
	ld	c,27
	call	vidout
	ld	c,'C'
	call 	vidout
	ld	c,'6'
	call	vidout
	ld	a,32
	ld	(row),a			;re initialize (row) for next dump
	jp	entry			;return for next char


CRLF:	ld	c,0dh			;routine to output newline
	call	print
	ld	c,0ah
	call	print
	ret

print:	push	af			; routine to put char to LST: device
	push	bc
	push	de
	push	hl
	call	prntout
	pop	hl
	pop	de
	pop	bc
	pop	af
	ret

advid:	ld	a,18			; routine to give address in hl
					; to Video controller
	out	(1Ch),a
	ld	a,h
	out	(1Dh),a
	ld	a,19
	out	(1Ch),a
	ld	a,l
	out	(1Dh),a
	ld	a,31
	out	(1Ch),a
	ret
	nop
codend	equ	$
	end