;
;************************************************************
;*                                                          *
;*           Simple BIOS Listing                            *
;*                                                          *
;************************************************************
;
;
#define	version		"0"     	;Equates used in the start up message
#define	month		"11"
#define	day		"XX"
#define	year		"2007"
#define	sys		"CP/M 2.2."
#define os_type		"for the Tandy"
#define	DEF_NEED_DBLK	080h

cr	.equ	0Dh              
lf	.equ	0Ah 
OUT	.equ	0D3h	
RET	.equ	0C9h            

;************************************************************
;*                                                          *
;*           BIOS JMP listing                               *
;*                                                          *
;************************************************************

	.org    Start               ;Assemble code at BIOS address

	jmp	Boot   		;Cold boot
	jmp	Wboot		;Warm boot
	jmp	Const		;Console status -- returns A = 0FFH if there is a
				;  console keyboard character waiting
	jmp	Conin		;Console input -- returns the next console keyboard
				;  character in A
	jmp	Conout		;Console output -- outputs the character in C to



	.org	Start+512


Signon_Message:           	;Main sign-on message
	.db	sys
	.db	version         ;Current version number
	.db	" "
	.db	os_type
	.db	os_type_version
	.db	" "
	.db	year            ;Current date
	.db	"-"
	.db	month
	.db	"-"
	.db	day
	.db	cr
	.db	0

;************************************************************
;*                                                          *
;*           Init hardware                                  *
;*                                                          *
;************************************************************

Initialize_Stream:      	;This stream of data is used by the
				;initialize subroutine.  It has the following
				;format:
				;
				;       DB       Port number to be initialized
				;       DB       Number of bytes to be output
				;       DB       xx,xx,xx,xx data to be output
				;       :
				;       :
				;       DB       Port number of 00H terminator

	.db	0
Boot:
	di

	lxi	sp, DEF_STACK_TOP

	mvi	a, OUT					;Set up OUT
	sta	DEF_STACK_TOP - DEF_STACK_SIZE + 1
	mvi	a, RET					;Set up RET
	sta	DEF_STACK_TOP - DEF_STACK_SIZE + 3	

	lxi	h,Initialize_Stream
Initialize_Loop:
   	mov	a,m					;Get port number
	ora     a					;If 0, then initialization complete
	jz	Initialize_Complete
	inx	h					;HL -> Count of number of bytes to output
	mov	c,m					;Get byte count

Initialize_Next_Byte:
	inx	h					;HL -> Next data byte
	mov	a,m					;Get next data byte
	sta	DEF_STACK_TOP - DEF_STACK_SIZE + 2
	call	Wait_lcd_not_busy
	call	DEF_STACK_TOP - DEF_STACK_SIZE + 1	;Output to correct port
	dcr	c					;Count down
	jnz	Initialize_Next_Byte			;Go back if more bytes
	inx	h					;HL -> Next port number
	jmp	Initialize_Loop				;Go back for next port initialization
;
Initialize_Complete:
Wboot:
	mvi	a,00000001B				;Set IOBYTE to indicate terminal
	sta	IOBYTE					;  is to act as console

	xra	a					;Set default disk drive to A:
	sta	Default_Disk
	sta	LCD_ROW
	sta	LCD_COL
	sta	INBUFF+1
	sta	OUTFLAG
	sta	PRTFLAG

	mvi	a,127
	sta	INBUFF
 
	lxi	h,Signon_Message			;Display sign-on message on console
	call	Display_Message
;
;	ei						;Interrupts can now be enabled
;
Enter_CPM2:
	jmp    COMMAND				;Complete initialization and enter
			 				;  CP/M by going to the Console Command
			 				;  Processor.
Const:
	ret


;	### Bios functions

Display_Message:		;Displays the specified message on the console.
				;On entry, HL points to a stream of bytes to be
				;  output.  A zero byte terminates the message.
	mov	a,m		;Get next message byte
	ora	a		;Check if terminator
	rz			;Yes, return to caller
	mov	c,a		;Prepare for output
	push	h		;Save message pointer
	call	Conout		;Go to main console output routine
	pop	h		;Recover message pointer
	inx	h		;Move to next byte of message
	jmp	Display_Message	;Loop until complete message output

Wait_lcd_not_busy:
	ret


.include "conout.asm"
.include "conin-rs.asm"

seldsk:				;Select disk in C
				;C = 0 for drive A, 1 for B, etc.
				;Return the address of the appropriate
				; disk parameter header in HL, or 0000H
				; if the selected disk does not exist.
				;
	lxi	h,0		;Assume an error
	mov	a,c		;Check if requested disk valid
	cpi	DEF_NUMBER_DISKS
	rnc			; Return if > maximum number of disks

	sta	SELECTED_DISK	;Save selected disk number
				;Set up to return DPH address
	jz	seldskram
	mov	l,a             ;Make disk into word value
	mvi	h,0
				;Compute offset down disk parameter
				; header table by multiplying by
				; parameter header length (16 bytes)
	dad	h		; *2
	dad	h		; *4
	dad	h		; *8
	dad	h		; *16
	lxi	d,DEF_DISK_PARM	;Get base address
	dad	d		;DE -> Appropriate DPH
	push	h		;Save DPH address
;
				;Access disk parameter block
				; to extract special prefix byte that
				; identifies disk type and whether
				; deblocking is required
				;
	lxi	d,10		;Get DPB pointer offset in DPH
	dad	d		;DE -> DPB address in DPH
	mov	e,m		;Get DPB address in DE
	inx	h
	mov	d,m
	xchg			;DE -> DPB
	dcx	h		;DE -> prefix byte
	mov	a,m		;Get prefix byte
	ani	0fh		;Isolate disk type
	sta	DISK_TYPE	;Save for use in low-level driver
	mov	a,m		;Get another copy of prefix byte
	ani	DEF_NEED_DBLK	;Isolate deblocking flag
	sta	DBLK_REQ	;Save for use in low-level driver
	pop	h		;Recover DPH pointer
	ret

seldskram:
	ret

DEF_DISK_PARM:
	.dw	DEF_RAM_DISK
	.dw	0
	.dw	0
	.dw	0				;Reserved for CP/M
	.dw	DIRECTORY_BUFFER
	.dw	0				;Parm block
	.dw	0				;work area
	.dw	0				;alocation vector

DEF_RAM_DISK:
	.dw	0

DEF_RAM_DISK_BLOCK:
	.dw	72             ;128-byte sectors per track
	.db	4              ;Block shift
	.db	15             ;Block mask
	.db	1              ;Extent mask
	.dw	174            ;Maximum allocation block number
	.dw	127            ;Number of directory entries - 1
	.db	11000000B      ;Bit map for reserving 1 alloc. block
	.db	00000000B      ;  for file directory
	.dw	32             ;Disk changed work area size
	.dw	1              ;Number of tracks before directory