Atari 400 Technical Reference Manual page 369

ERR LINE AD DR 81 82 83 84 DISPLAY HANDLER -- 10-30-78
DISPLC PAGE 108
4785 F957
A9 00 LDA #0
4786 F959 85 67 STA MLTTMP+l
4787 F958 A5 66 LDA MLTTMP
i
QUICK X8
4788 F95D
OA
ASL A
4789 F95E
26 67 ROL MLTTMP+l
4790 F960 85 51 STA HOLDl
i
(SAVE 2X VALUE)
4791 F962 A4 67 LDY MLTTMP+1
• If II
,
4792 F964 8C 9F 02 STY HOLD2
• UII
,
4793 F967
OA ASL A
4794 F968 26 67 ROL MLTTMP+l
4795 F96A OA ASL A
4796 F968
26 67 ROL
MLTTMP+l
4797 F96D
18 CLC i ADD IN 2X
4798 F96E 65 51 ADC HOLDl
4799 F970
85 66
STA
MLTTMP
4800 F972 A5 67 LDA MLTTMP+1
4801 F974 6D 9F 02
ADC HOLD2
4802 F977
85 67 STA MLTTMP+1
4803 F979 A6 57 LDX DINDEX
iNOW
SHIFT MLTTMP LEFT DHLINE TIMES TO FINIS
4804 F97B BC 81 FE LDY DHLINE,X
i
MULTIPLY
4805 F97E
88
CONVR1: DEY
i
LOOP N TIMES
4806
F97F
30 07 BMI CONVR2
4807 F981 06 66 ASL MLTTMP
4808 F983 26 67 ROL MLTTMP+l
4809 F985 4C 7E F9 JMP CONVR1
4810 F988
BC A5 FE CONVR2: LDY DIV2TB,X iNOW DIVIDE HCRSR TO ACCOUNT FOR PARTIAL BYT
4811 F98B A5 55 LDA COLCRS
4812 F98D A2 07 LDX #7
i
*
TRICKY
*
4813 F98F 88 CONVR3: DEY
4814 F990 30 OA BMI CONVR4
4815 F992 CA DEX
4816 F993 46 56
LSR COLCRS+l
4817 F995
6A ROR A
4818 F996 6E Ai 02 ROR TMPLBT iSAVE LOW BITS FOR MASK
4819 F999 4C 8F F9
JMP CONVR3
4820 F99C
C8 CONVR4: INY
iSO
Y IS ZERO UPON RETURN FROM THIS ROUTINE
4821 F99D 18 CLC
4822 F99E 65 66 ADC MLTTMP
iADD SHIFTED COLCRS TO MLTTMP
4823 F9AO
85 66 STA MLTTMP
4824 F9A2 90 02 BCC CONVR5
4825 F9A4 E6 67 INC MLTTMP+l
4826 F9A6
38 CONVR5: SEC
i
*
TRICKY
*
4827 F9A7
6E A1 02 CONVR6: ROR TMPLBT iSLIDE A "1\1 UP AGAINST LOW BITS (CONTINUE T
4828 F9AA 18 CLC
4829 F9AB CA DEX
iAND FINISH SHIFT SO LOW BITS ARE
4830
F9AC
10 F9 BPL CONVR6 iRIGHT JUSTIFIED.
4831
F9AE
AE Ai 02 LDX TMPLBT iTMPLBT IS NOW THE INDEX INTO DMASKTB
4832 F9B1 A5 66
LDA MLTTMP ; PREPARE FOR RETURN
4833 F9B3
18 CLC
4834 F9B4 65 64 ADC ADRESS
4835 F9B6 85 64 STA
ADRESS
4836 F9B8
85 5E STA OLDADR iREMEMBER THIS ADDRESS FOR CURSOR
4837 F9BA
A5 67 LDA MLTTMP+l
4838 F9BC
65 65 ADC ADRESS+1