\xcd\x03\x800\x01v\xff\xd5
Note that non-ascii characters in the above source code will be escaped (such as \x9f).
Disassemble:
ORG 00000H CALL 08003H ;0000 CD 03 80 . . . JR NC,$+3 ;0003 30 01 0 . HALT ;0005 76 V RST 38H ;0006 FF . PUSH DE ;0007 D5 .