IBM PC CONVERTIBLE - Page 120

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042A
A8 01 TEST AL, HORLRETRACE IS IT HIGH
74 FB JZ P3 WAIT UNTIL IT IS
AD LODSW GET THE CHAR/ATTR
E9 016F R JMP
VIDEO_RETURN
READ....ACCURRENT ENDP
FIND_POSITION
PROC NEAR
8A CF
MOV
CL, BH DISPLAY PAGE TO CX
32 ED
XOR CH, CH
8B F1 MOV SI,CX MOVE TO SI FOR INDEX
01 E6 SAL SI,I ; * 2 FOR WORD OFFSET
8B 84 0050 R MOV AX, [SI+ OFFSET CURSOR_POSN- ; GET ROW/COL OF PAGE
33 DB XOR BX, BX SET START ADDRESS TO ZERO
E3 06 JCXZ P5
NO_PAGE
P4:
PAGE_LOOP
03 1E 004C R
ADD BX,CRLLEN
LENGTH OF BUFFER
E2 FA LOOP P4
P5:
NO_PAGE
E8 02E6 CALL POSITION DETERMINE LOCATION IN REGEN
03 08 ADD BX ,AX ADD TO START OF REGEN
C3 RET
FI ND_POS IT ION
ENDP
WRITE....ACCURRENT
80 FC 04
72 08
80 FC 07
74 03
E9 05BD R
8A E3
50
51
E8 03EO R
8B FB
59
5B
INPUT
OUTPUT
THIS ROUTINE WRITES THE ATTRIBUTE
AND CHARACTER AT THE CURRENT CURSOR
POSITION
(AL) = CHAR TO WRITE
(BH) = DISPLAY PAGE
(BL) = ATTRIBUTE OF CHAR TO WRITE
(CX) = COUNT OF CHARACTERS TO WRITE
(AH) = CURRENT CRT MODE
(OS) DATA SEGMENT
(ES) REGEN SEGMENT
NONE
INTERRUPTS: DISABLED DURING THE WRITE
WRlTE....ACCURRENT
PROC NEAR
CMP
AH,4 IS TH I S GRAPH I CS
JC
P6
CMP AH,7
IS THIS MONO CARD
JE
P6
JMP GRAPHICS_WRITE
P6: WRITE....ACCONTINUE
MOV AH, BL GET ATTRI BUTE TO AH
PUSH AX SAVE CHAR/ATTRIBUTE
PUSH CX SAVE WRITE COUNT
CALL
FIND_POSITION
MOV 01, BX ADDRESS TO 01 REGISTER
POP CX WRITE COUNT
POP BX CHARACTER/ A TTR IN BX REG
P7 : WRITE_LOOP
;----- WAIT FOR HORIZONTAL
RETRACE
8B 16 0063 R MOV OX ,ADDR_6845 GET BASE ADDRESS
83 C2 06 ADD DX,6 POINT AT STATUS PORT
9C PUSHF SAVE CURRENT FLAGS
P8:
EC IN AL,DX GET STATUS
A8 01 TEST AL, HORLRETRACE IS IT LOW
75 FB JNZ P8 WAIT UNTIL IT IS
FA CLI NO MORE INTERRUPTS
P9:
EC IN AL,DX GET STATUS
A8 01 TEST AL, HORLRETRACE IS IT HIGH
74 FB JZ P9 WAIT UNTIL IT IS
8B C3 MOV AX,BX RECOVER THE CHAR/ATTR
AB STOSW PUT TH E CHAR/ A TTR
90 POPF INTERRUPTS BACK ON - I F em
ROM BIOS 2-95