YRW-801 analysis

Por Eugeny_Brychkov

Paragon (1173)

imagem de Eugeny_Brychkov

09-02-2021, 16:34

I am analysing the contents of the OPL4 ROM, and it seems I am missing something. There're instruments overlapping each other (316 to 330 overlap other instruments), and I calculated 626 kB of unused space (out of 2 MB), not related to any instrument with proper layout. At the same time these unused locations contain some non-uniform bytes. Invalid instrument 330 refers to the wave data with "YAMAHA.YMH" in it, which must not be valid wave data.

Anyone have done this ROM analysis before? Findings?

Entrar ou registrar-se para comentar

Por Eugeny_Brychkov

Paragon (1173)

imagem de Eugeny_Brychkov

10-02-2021, 11:13

I have made mistake in calculating the allocation of samples. After correction ROM is having just 229 bytes of unused space.

Por Grauw

Ascended (9899)

imagem de Grauw

10-02-2021, 11:16

Good, that makes more sense!

Por sdsnatcher73

Paragon (1972)

imagem de sdsnatcher73

11-02-2021, 13:41

So what are your goals for this analysis? I am genuinely curious. Any other findings so far other than the unused space in the ROM?

Por Eugeny_Brychkov

Paragon (1173)

imagem de Eugeny_Brychkov

11-02-2021, 15:08

I needed 24 bytes at the end of the ROM. It appeared that there're only 4 unused bytes at the end, and they are also not actually unused, but identifiers of the ROM version. And second task was to validate the contents and ensure I understand the layout.