I used to do that kind of hacking in the 80's. I recognized the CALL-151. I have an old Apple II+ in the other room I'm tempted to try firing up just to solve this mystery.
NEW
1HOME:A=9200:B=13168:C=100:FORI=768TO796:READN:POKEI,N:NEXT:HGR:POKE-16302,0:HCOLOR=4:HPLOT0,0:CALL62454:HCOLOR=2:HPLOT0,63TO279,63:HPLOT0,62TO279,62:HCOLOR=6:HPLOT0,61TO279,61:HPLOT0,60TO279,60:HCOLOR=1:HPLOT0,59TO279,59:HPLOT0,58TO279,58
2HCOLOR=5:HPLOT0,55TO279,55:HPLOT0,54TO279,54:HCOLOR=0:HPLOT0,123TOC,123:HPLOT0,122TOC,122:HPLOT0,119TOC,119:HPLOT0,118TOC,118:COLOR=0:FORI=0TO39:VLIN0,39ATI:NEXT:COLOR=13:HLIN0,39AT14:FORI=0TO7:POKEA+I,0:POKEB+I,0:NEXT:COLOR=1
3HLIN0,39AT13:VTAB21:PRINTTAB(16)"RAINBOW":PRINT:PRINT"MIXED GRAPHICS (HI-RES/COLOR)":CALL768:DATA173,87,192,173,83,192,173,84,192,173,80,192,208,251,173,86,192,160,22,136,208,253,234,173,87,192,76,9,3
RUN CALL -151
0300- AD 30 C0 LDA $C030
0303- 20 ED FD JSR $FDED
0306- 4C 00 03 JMP $0300
300G