BlueSCSI toolbox makes emulated Mac unresponsive and fails to download files

[beholdnec]

Describe the bug
When I try to use File Sharing on an emulated IIx, the BlueSCSI toolbox hangs.

I believe this issue is not related to #228 since it does not emit an illegal instruction and the machine is a IIx, not an SE/30.

The emulated machine becomes very slow and unresponsive (0.7x max speed). I cannot click anything on the screen, but the cursor still moves. The download never progresses past 0%. The emulator is stuck until I stop, reset, or close Snow.

In a Debug build, the console fills up with the message:

[2026-03-23T01:22:35Z WARN  snow_core::mac::macii::bus] Read from unimplemented address: 7818D3B0
[2026-03-23T01:22:35Z WARN  snow_core::mac::macii::bus] Read from unimplemented address: 7818D3B1
[2026-03-23T01:22:35Z WARN  snow_core::mac::macii::bus] Read from unimplemented address: 7818D3B2
[2026-03-23T01:22:35Z WARN  snow_core::mac::macii::bus] Read from unimplemented address: 7818D3B3

The address continually increases.

To Reproduce

1. Set up a Macintosh IIx with standard ROMs.
2. Boot a System 7.5.3 disk.
3. From the Tools -> File sharing menu, select a folder.
4. From the Tools -> File sharing menu, insert the toolbox floppy.
5. Launch the BlueSCSI SD Transfer program.
6. Select a file and click Download.

Configuration
Version of Snow you are running (from the title bar): Snow v1.3.1-c45324d (latest commit at time of writing)
Host operating system: Windows 11
Macintosh model you are emulating: IIx, 32 MB
OS you are emulating, including version and extensions (if relevant): System Software 7.5.3 Revision 2.

[twvd]

I finally managed to reproduce this. It only occurs if the BlueSCSI Toolbox is runs from the toolbox floppy, which is not ment to happen anyway, because the floppy is write-protected. Still, it shouldn't crash.

Sometimes, I also get this message, rather than a crash:

Anyway, @beholdnec you are ment to copy the Toolbox off the floppy, then it works.

@erichelgeson any idea on the crash of the toolbox?

[erichelgeson]

I didn't consider the app would run on a locked file system. I think it should be trivial to add a check and let the user know vs crash/err number. Try to get to it later this week.

[classilla]

Interesting, because on the release version of Snow I consistently got the -44 error until I figured out I had to copy it somewhere first. Maybe make that particular message more verbose?

[erichelgeson]

done - there's a new beta published on my site. 1.1 should be final soon, waiting on one item from someone.