3F30 through 3F9F are definitely NOT opcodes, for example.
"PROGRAM,WE WOULD TEACH YOU.*****TEL.TOKYO-JAPAN 044(244)2151 EXTENTION 304 SYSTEM DESIGN IKEGAMI CO. LIM."
So that section is just HEX codes for ASCII text characters. (50 is HEX for "P", 52=R, 4F=O, etc.)
But the disassembler translated them in terms of the Z80 opcode instruction set, so in the disassembled file it reads as
3f30 50 LD D,B
3f31 52 LD D,D
3f32 4F LD C,A
My disassembly might be full of problems like that, or might not be, because I don't know what I'm doing, or what I'm reading. I don't know how to differentiate what's actually machine code from what's junk. Probably very little junk in here though, I would assume, since the whole program had to fit into 16K.