IBM PC CONVERTIBLE - Page 121

042B E2 E7
0420 E9 016F R
0430
0430
0430
80 FC 04
0433
72 08
0435 80 FC 07
0438 74 03
043A E9 05BD R
0430
0430
50
043E
51
043F E8 03EO
0442 8B FB
0444 59
0445 5B
0446
LOOP P7
AS MANY TIMES AS REQUESTED
JMP V IDEO_RETURN
WRITE-AC_CURRENT ENDP
WRITE_CCURRENT
** NOT VALID FOR MEDIUM RESOLUTION GRAPHICS **
THIS ROUTINE WRITES THE CHARACTER AT
THE CURRENT CURSOR POSITION, ATTRIBUTE
INPUT
OUTPUT
UNCHANGED
(BH) = DISPLAY PAGE
(CX) = COUNT OF CHARACTERS TO WRITE
(AL) = CHAR TO WRITE
(AH) CURRENT CRT MODE
(OS) = DATA SEGMENT
(ES) = REGEN SEGMENT
NONE
INTERRUPTS: DISABLED DURING THE WRITE
WRITE_CCURRENT PROC
NEAR
CMP AH,4 IS THIS
GRAPHICS
JC PI0
CMP AH,7 IS THIS MONO CARD
JE PI0
JMP
GRAPHICS_WRITE
PI0 :
PUSH AX SAVE CHAR ON STACK
PUSH CX
SAVE WRITE COUNT
CALL FIND_POSITION
MOV
01, BX ADDRESS TO 01
POP
CX WRITE COUNT
POP
BX BL HAS CHAR TO WR I TE
Pll: WRITE_LOOP
; ----- WAIT FOR HORIZONTAL RETRACE
0446
8B 16 0063 MOV OX ,ADDR_6845
GET BASE ADDRESS
044A 83 C2 06 ADD
DX,6 POINT AT STATUS PORT
0440 9C PUSHF
SAVE CURRENT FLAGS
044E P12 :
044E EC IN AL,DX
GET STATUS
044F
A8 01 TEST AL,HORLRETRACE
IS IT LOW
0451 75 FB
JNZ P12
WAIT UNTIL IT IS
0453
FA CLI
NO MORE INTERRUPTS
0454
P13 :
0454 EC IN
AL,DX GET STATUS
0455 A8 01 TEST
AL,HORLRETRACE IS IT HIGH
0457 74 FB
JZ
P13
WAIT UNTI L IT IS
0459
8A C3 MOV
AL, BL RECOVER CHAR
045B AA
STOSB WRITE CHAR
045C 90 POPF
I NTERRUPTS BACK ON - I F ON
0450 47 INC
01 BUMP POINTER PAST ATTRIBUTE
045E E2 E6 LOOP Pll
AS MANY TIMES AS REQUESTED
0460 E9 016F R
JMP
VIDEO_RETURN
0463 WRITE_CCURRENT ENDP
2-96 ROM BIOS