;386以上微機適用
;純dos下才能使用
;tasm4.1或以上編譯
;*********************;
;*       8251        *;
;*********************;
 io_plx_device_id	equ 05406h	;TPC卡設備ID
 io_plx_vendor_id	equ 010b5h	;TPC卡廠商ID
 IO_PLX_SUB_ID		EQU 0905410B5H	;TPC卡子設備及廠商ID
  DATA51 EQU 208H-200H             ;8251A DATA PORT
  CTRL51 EQU 209H-200H             ;8251A COMMOND PORT
  TIMER2 EQU 202H-200H             ;8253 COUNT2
  TIMCTL EQU 203H-200H             ;8253 CTRL PORT
  CLK00  EQU 250              ;8251A CLK 250KHZ
  BPS00  EQU 1200             ;BPS=1200
  FACTOR EQU 16               ;8251A BPS FACTOR=16
data segment
 io_base_address	db 4 DUP(0)	;TPC卡I/O基地址暫存空間
 pcicardnotfind		db 0dh,0ah,'TPC pci card not find or address/interrupt error !!!',0dh,0ah,'$'
 iobaseaddress		db 0dh,0ah,'TPC pci card I/O Base Address : ','$'
 enter_return		db 0dh,0ah,'$'
 MES  DB 'NOW YOU CAN PLAY A KEY ON THE CPU_KEYBORD',0AH,0DH
      DB 'IT WILL DISPLAY ON THE TERMINAL_SCREEN' ,0AH,0DH
      DB 'OR YOU CAN PRESS A KEY ON THE TERMINAL KEYBOARD',0AH,0DH
      DB 'IT WILL DISPLAY ON THE CPU_SCREEN   ',0AH,0DH
      DB 'PRESS ESC_KEY CAN FINISH COMMUNICATION',0AH,0DH,'$'
data ends
stacks segment
 db 100 dup (?)
stacks ends
code segment
        assume cs:code,ds:data,ss:stacks,es:data
start:
.386
        cli
        mov ax,data
        mov ds,ax
        mov es,ax
        mov ax,stacks
        mov ss,ax
	call	findtpc		;查找TPC卡資源并顯示

        CALL SET_BPS		;初始化8253
        CALL INIT51
        MOV AX,DATA            ;DISPLAY MES
        MOV DS,AX
        LEA DX,MES
        MOV AH,09
        INT 21H
FOREVER:
	MOV  DX,word ptr io_base_address
	add  dx,CTRL51
	IN  AL,DX
	TEST AL,02
	JNZ RECEIVE
	MOV AH,01              ;INPUT A CHAR FROM CPU_KEYBORD
	INT 16H
	JZ  FOREVER
	MOV AH,0
	INT 16H
	CMP AL,1BH
	JZ EXIT
	MOV  DX,word ptr io_base_address
	add  dx,DATA51
	OUT DX,AL              ;CPU OUTPUT THE CHAR TO 8251A
	mov dl,al
	mov ah,02
	int 21h
	JMP FOREVER
RECEIVE:
	MOV  DX,word ptr io_base_address
	add  dx,DATA51
	IN  AL ,DX
	CMP AL,1BH
	JZ  EXIT
	MOV DL,AL
	inc dl
	MOV AH,02
	INT 21h
	JMP FOREVER
EXIT:   MOV AX,4C00H
	INT 21H		;退出

INIT51 PROC NEAR             ;INIT 8251A
	MOV  DX,word ptr io_base_address
	add  dx,CTRL51
	XOR AX,AX
	MOV CX,03
LL:	CALL CHAROUT
	LOOP LL
	MOV AL,40H            ;RESET 8251A
	CALL CHAROUT
	mov al,4eh            ;DATA 8 BIT,STOP 1 BIT,FACTOR=16
	call charout
	MOV AL,27H            ;ENABLE INPUT AND OUTPUT
	CALL CHAROUT
	RET
INIT51 ENDP

CHAROUT PROC NEAR	;OUTPUT A BYTE
	OUT DX,AL
	PUSH CX
	MOV CX,20h
GG:	LOOP GG
	POP CX
	RET
CHAROUT ENDP

SET_BPS PROC NEAR           ;T/R CLOCK FROM TIMER2
	MOV DX,0
	MOV AX,CLK00
	MOV BX,1000             ;COUNT2=CLK00*1000/FACTOR/BPS00
	MUL BX
	MOV BX,BPS00
	DIV BX
	MOV DX,00
	MOV BX,FACTOR
	DIV BX
	MOV BX,AX
	MOV  DX,word ptr io_base_address
	add  dx,TIMCTL           ;TIMER2 IN MODE3
	MOV AL,0B6H
	OUT DX,AL
	MOV  DX,word ptr io_base_address
	add  dx,TIMER2
	MOV AX,BX
	OUT DX,AL
	MOV AL,AH
	OUT DX,AL
	RET
SET_BPS ENDP

findtpc proc near		;查找TPC卡資源并顯示
	pushad
	pushfd
	MOV	AX,0B101H
	INT	1AH
	JC	findtpc_notfind		;檢查PCI BIOS是否存在

	MOV	AX,0B102H
	MOV	CX,io_plx_device_id
	MOV	DX,io_plx_vendor_id
	MOV	SI,0
	INT	1AH
	JC	findtpc_notfind		;檢查TPC卡是否安裝,設備號、廠商號

	MOV	AX,0B10AH
	MOV	DI,02CH
	INT	1AH
	JC	findtpc_notfind
	CMP	ECX,IO_PLX_SUB_ID
	JNZ	findtpc_notfind		;檢查TPC卡是否安裝,子設備號、廠商號

	MOV	AX,0B10AH
	MOV	DI,18H
	INT	1AH
	JC	findtpc_notfind		;讀TPC卡I/O基址信息
	mov	dword ptr io_base_address,ecx
	and	ecx,1
	jz	findtpc_notfind		;檢查是否為i/o基址信息
	mov	ecx,dword ptr io_base_address
	and	ecx,0fffffffeh
	mov	dword ptr io_base_address,ecx	;去除i/o指示位并保存

	mov	dx,offset iobaseaddress		;顯示i/o提示信息
	mov	ah,09h
	int	21h
	mov	ax,word ptr io_base_address
	call	dispword			;顯示i/o基地址

	mov	dx,offset enter_return		;加回車符,換行符
	mov	ah,09h
	int	21h
	popfd
	popad
	ret
findtpc_notfind:
	mov dx,offset pcicardnotfind		;顯示未找到tpc卡提示信息
	mov ah,09h
	int 21h
	mov ax,4c00h
	int 21h		;退出
findtpc endp

dispword proc near		;顯示子程序
	push dx
	push cx
	push bx
	mov cx,4
	mov bx,16
dispword_loop1:
	push ax
	push cx
	sub bx,4
	mov cx,bx
	shr ax,cl
	and al,0fh	;首先取低四位
	mov dl,al
	cmp dl,9	;判斷是否<=9
	jle dispword_num		;若是則為'0'-'9',ASCII碼加30H
	add dl,7	;否則為'A'-'F',ASCII碼加37H
dispword_num:
	add dl,30h
	mov ah,02h	;顯示
	int 21h
	pop cx
	pop ax
	loop dispword_loop1
	pop bx
	pop cx
	pop dx
	ret		;子程序返回
dispword endp
code ends
end start