IBM 5150 Hardware Reference Manual page 248

LaC OBJ LINE SOURCE
f41C 74F8
3986
JZ P13
; WAIT UNTIL IT IS
F41£ BAC3 3987 MDV
AL,BL
; RECOVER CHAR
F420 AA 3968 SlOSS
; PUT THE CHAR/ATTR
F421 47 3989 INC
Dr
; BUNP POINTER PAST ATTRIBUTE
F422 E2E8
3990
LOOP P11
; AS MANY TII1ES AS REQUESTED
F424 E9AOFD 3991
JMP
VIDEO_RETURN
3992
WRITE_C_CURRENT EHOP
3993
j - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ­
3994
j
READ DOT -- WRITE DOT
3995 ; THESE ROUTINES WIll WRITE A DOT. OR READ THE
3996 DOT AT THE INDICATED LOCATION
3997 ENTRY - ­
399S OX
=
ROW (0-199) (THE ACTUAL VALUE DEPENDS ON THE MODE)
3999 C'I(
=
COLUMN ( 0-639) ( THE VALUES ARE NOT RANGE CHECKED)
4000 Al
=
DOT VALUE TO WRITE (I. 2 OR 4 BITS DEPENDING ON MODE.
4001 REQ'D
FOR
WRITE DOT ONLY. RIGHT JUSTIFIED)
4002
BIT 7
OF AL : 1 INDICATES
XOR WE
VALUE INTO THE LOCATION
4003 OS
=
DATA SEGMENT
4004 ES
=
REGEN SEGMENT
4005
4000 EXIT
4007 AL :: DOT VALUE REAO, RIGHT JUSTIFIED, READ ONLY
4008 J ------------------------- ------------------­
4009 ASSUME CS :CODE .DS:DATA. ES: DATA
F427 4010 REAO_oDT PROC NEAR
F427 E83100 4011
CALL
03 • DETERMINE BYTE POSITION Of DOT
F42A 268A04 4012 HOV AL,ES:(SIJ ; GET THE BYTE
F420 22C4 4013 AND
AL.AH
• MASK OFf THE OTHER BITS IN THE BYTE
F42F 02EO
4014
SHL
AL,CL
; LEFT JUSTIfY THE VALUE
F431 8ACE
4015
HDV
Cl,DH ; GET NUMBER OF BITS IN RESULT
F433 02CO 4016
OOL AL,CL
; RIGHT JUSTIFY THE RESULT
F435 E98FFD
4017 JHP VIDEO.RETURN
; RETURN FROM VIDEO 10
4018 ENOP
4019
F436
4020 IomITE.DOT PROC NEAR
F438 50 4021 PUSH
AX SAVE DOT VALUE
1"""""\
F439 50 4022 PUSH AX TWICE
F43A E61EOO
4023 CALL R3 DETERMINE BYTE POSITION OF THE ~OT
F430 02E8 4024
SHR
AL.CL SHIFT TO SET UP THE BITS fOR OUTPUT
F43F 22C4 4025
Mm
AL.AH STRIP OfF THE OTHER BITS
F441 268AOC
4026 MOV
CL,ES:[SI1 ; GET THE CURRENT BYTE
F444 58 4027
POP
BX ; RECOVER XOR flAG
F445 F6C380 4028 TEST BL.80H
; IS IT ON
F448 750D 4029 JNZ ; YES. XOR THE DOT
.,
F44A F604 4030
NOT
AH
; SET THE MASK TO REMOVE THE INDICATED BITS
F44C 22CC
4031
AND CL,AH
F44E QAel 4032 00 AL.CL ; OR IN THE NEW VALUE OF THOSE BITS
F450 4033 Rl : ; FINISH_DOT
F450 268804 4034 MOV ES:(SI1.AL ; RESTORE THE BYTE IN MEMORY
F453 58
4035
rop
AX
F454 E970FO 4036 JMP VIDEO.RETURN ;
RETURt~
FROM VIDEO
10
F457 4037
R2 ; ; XOR_OOT
F457 32Cl 4038
XOO
AL,CL ; EXCLUSIVE
OR
THE DOTS
.,
F459 ESFS 4039 JMP ; FINISH UP THE W1HTWG
4040
WRITE.DOT
ENOP
4041 ; ----------------------- --------------------­
4042 ; THIS SUBROUTINE DETERMINES THE REGEN BYTE LOCATION OF THE
4043 ; IHDICATED ROW COLUMN VALUE IN GRAPHICS MODE.
4044 ENTRY - ­
4045 OX :: ROW VALUE (0-1991
4046
ex
=
COLUMN VALUE (0-639)
4047 EXIT - ­
4048 51 ;: OFFSET INTO REGEN BUFFER FOR BYTE OF INTEREST
4049
AH
=
MASK TO STRIP OFF THE BITS OF INTEREST
4050
CL ::; BITS TO SHIFT TO RIGHT JUSTIFY THE MASK IN AH
4051
CH
=
# BITS IN RESULT
4052:
j - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ­
F458 4053 03
PROC HEAR
F4SB 53 4054
PUSH BX ; SAVE
ex
OURING OPERATION
F45C 50
4055 PUSH AX ; WILL SAVE AL DURING OPERATION
4056
4057 ;------ DETERMINE 1ST BYTE IN IDICATEO ROW BY MULTIPLYING ROW VALUE BY 40
4058 ;------ ( LOW BIT OF ROW DETERMINES EVEN/ODD. 80 BYTES/ROW
4059
F450 B028
4060 MOV AL.40
F45F 52 4061
PUSH
OX ; SAVE ROW VALUE
A-55