使用proteus仿真点阵滚屏显示为何会出现拖影？

正常情况显示是这样的，但是跑着跑着，列里就会出现拖影，周的竖都会变成两列甚至三列
但是再跑几个循环，又恢复了正常，像这样往复。我想问一下这是proteus仿真的问题还是程序的问题？使用4片74HC595进行移位寄存。
DATAH EQU 60HDATAL EQU 62HCOL EQU 64HCOL2 EQU 65HTEMP EQU 68HDL EQU P1.0DH EQU P1.1CLK EQU P1.2OE EQU P1.3SCK EQU P1.4
ORG 0000HLJMP MAINORG 0100HMAIN:MOV COL,#16MOV R1,#8MOV R2,#16LCALL READLJMP MAINDISPLAY:MOV COL2,#16CLR OECLR SCKMOV TEMP,DATAHMOV TEMP+1,DATAH+1BACK:CLR CLKSETB CMOV A,DATAHRRC AMOV DATAH,AMOV A,DATAH+1RRC AMOV DATAH+1,AMOV DH,CCLR CMOV A,DATALRRC AMOV DATAL,AMOV A,DATAL+1RRC AMOV DATAL+1,AMOV DL,CSETB CLKDJNZ COL2,BACKMOV DATAH,TEMPMOV DATAH+1,TEMP+1SETB SCKCLR SCKRETREAD:MOV DPTR,#SEGTABMOV R0,#00HLOOP1:MOV DATAH,#7FHMOV DATAH+1,#0FFHLOOP2:MOV A, R0MOVC A,@A+DPTRMOV DATAL,AINC R0MOV A, R0MOVC A,@A+DPTRMOV DATAL+1,ALCALL DISPLAYINC R0SETB CMOV A,DATAHRRC AMOV DATAH,AMOV A,DATAH+1RRC AMOV DATAH+1,ADJNZ COL,LOOP2MOV A, R0CLR CSUBB A,#32MOV R0,AMOV COL,#16DJNZ R1,LOOP1MOV R1,#8INC R0INC R0DJNZ R2,LOOP1MOV R2,#16SETB OERET
ORG 0500HSEGTAB:DB 00H,01H,00H,06H,7FH,0F8H,41H,00H,49H,00H,49H,78H,49H,48H,7FH,48HDB 49H,48H,49H,78H,49H,02H,41H,01H,7FH,0FEH,00H,00H,00H,00H,00H,00HDB 00H,01H,00H,06H,7FH,0F8H,41H,00H,49H,00H,49H,78H,49H,48H,7FH,48HDB 49H,48H,49H,78H,49H,02H,41H,01H,7FH,0FEH,00H,00H,00H,00H,00H,00H
END

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