Code
./build/mingw-gcc/bin/x64/Debug/unidasm.exe -arch m6805 -skip 0x100 -count 39 -basepc 0x100 roms/Tiger-Heli_with_MCU/68705brian.bin 
100: 9c        rsp
101: a6 ff     lda   #$FF
103: b7 04     sta   $04
105: b7 05     sta   $05
107: b7 01     sta   $01
109: b7 00     sta   $00
10b: a6 00     lda   #$00
10d: b7 06     sta   $06
10f: 15 01     bclr  2, $01
111: a6 73     lda   #$73
113: b7 00     sta   $00
115: 14 01     bset  2, $01
117: 9a        cli
118: 20 fe     bra   $118
11a: 9d        nop
11b: 9d        nop
11c: 9d        nop
11d: 9d        nop
11e: 9d        nop
11f: 9d        nop
120: cd 01 30  jsr   $0130
123: cd 01 50  jsr   $0150
126: 80        rti
Works just fine. As long as you give it a recognised -arch and a filename it will produce disassembly. The usage message tells you you need to give it -arch and a filename.