.!\xcd\x03\x80\xfe" \x01\xeb\xbd0\xff\x10\xf3v
Note that non-ascii characters in the above source code will be escaped (such as \x9f).
Disassemble:
ORG 00000H LD L,021H ;0000 2E 21 . ! CALL 08003H ;0002 CD 03 80 . . . CP 022H ;0005 FE 22 . " JR NZ,$+3 ;0007 20 01 . EX DE,HL ;0009 EB . CP L ;000A BD . JR NC,$+1 ;000B 30 FF 0 . DJNZ $-11 ;000D 10 F3 . . HALT ;000F 76 V