.D81 works, physical disc does not: Luma

realbobele · Jun 19th 2025

I did load Luma from the Filehost. The .D81 contains two files. Loading the first runs the game, which then accesses the disc to load additional Data. Everything works fine.

I then copied those two files to a physical disc. Loading the game itself works, after running it you can hear the drive trying to access data but it immediately stops and the game starts with scrambeled graphics. Tried several discs, copying the files themselves or making a backup… never works.

Can somebody reproduce this behavior and maybe explain the different results to me?

Thanks and have a nice day

Boris

SirGeldi · Jun 19th 2025

I don´t even find something called Luma on Filehost.

SkulleateR · Jun 19th 2025

Quote from SirGeldi

I don´t even find something called Luma on Filehost.

https://files.mega65.org?id=81…57-4fed-893a-99f836c63c1b

SkulleateR · Jun 19th 2025

Quote from realbobele

Can somebody reproduce this behavior

Yes I can, doesn´t work for me either ...

First I thought it was similar to the problem I had with TEMPUS but after I tried all different loading methods including autoboot I don't think it is ...

Pyramidenkopf · Jun 19th 2025

I'm have the same problem with LUMA (and Mega Sisters as well). I've tried copying both games from SD card to real disk on the Mega64 and also tried writing the disk images to floppy disks on PC like I usually write all my 1581 disks. I couldn't produce working copies with either method.

Endurion · Jun 19th 2025

This could be the loader code used. I used Shallan's code for Mega Sisters too (Shallan is the author of Luma).

I believe it is basically expecting a .d81 image on the SD card as it's trying to read sector after sector. And those sectors even have to be right after each other. I should probably rework that some day.

I think I remember the main issue was I had no idea how to load a file to an address > $ffff directly.

realbobele · Jun 19th 2025

Quote from Endurion

This could be the loader code used. I used Shallan's code for Mega Sisters too (Shallan is the author of Luma).
I believe it is basically expecting a .d81 image on the SD card as it's trying to read sector after sector. And those sectors even have to be right after each other. I should probably rework that some day.
I think I remember the main issue was I had no idea how to load a file to an address > $ffff directly.

Thank you very much for the interesting details. This explains why simply copying the files over may break the games. Also most probably the BACKUP Command in BASIC does not clone the disk but just copy Files over. Then there is Floppy/D81 Imager from the Filehost, which seems to really copy Track by Track and Sector by Sector. But this does not work also.

So it seems there is no way for now to write an exact copy of a .D81 file to a physical disk with the M65… as long as I did not miss another way to do it.

kibo · Jun 19th 2025

The early loaders were derived from floppy loading examples that only worked on disk images but failed on real disks. I don’t recall 100% anymore but some registers behave simplified on virtual disks and the code was relying on that. The code needs to be adapted and tested on real disks. I think Showdown was a game that initially shipped on disks and could not even load because it was only tested on images in the emulator. There was a newer version provided later that fixed the loader code.

SkulleateR · Jun 20th 2025

Quote from realbobele

BACKUP Command in BASIC does not clone the disk but just copy Files over.

No, for me it looks like a sector copy, you can test by yourself by adding a random Byte onto an empty D81 and make a BACKUP. The random byte is also present on the destination D81 image without any files on there !