\x06\xf8>!\xff\x05 \xfcv
Note that non-ascii characters in the above source code will be escaped (such as \x9f).
Disassemble:
ORG 00000H LD B,0F8H ;0000 06 F8 . . LD A,021H ;0002 3E 21 > ! RST 38H ;0004 FF . DEC B ;0005 05 . JR NZ,$-2 ;0006 20 FC . HALT ;0008 76 V