#2165 VICE (x64sc) freezes with PRG from Larry's FLI Converter V187

[Felice Nardella]

VICE version:
Tested with many versions, including the latest official release VICE 3.9 (GTK and SDL).
The issue is reproducible on all tested builds.
Operating system:
Windows 11 Pro 64-bit.
The emulated C64 screen freezes right after starting the program.
VICE itself keeps responding normally (menus, window controls etc.), but the emulated machine is stuck.
While loading a .prg produced with Larry's FLI Converter V187 (2018), the program is recognized and loaded, but the emulated C64 freezes right after AUTOSTART: Entered ROM at $ea21, with no further activity.
Additional notes:
The issue occurs only with Larry's FLI Converter V187 (2018).
Files produced with more recent versions of the converter work fine and display correctly in VICE.
This suggests the freeze is triggered by something specific in the output of version 187.

[gpz]

The BASIC stub is missing a 0 at $081b

>C:0800  00 1a 08 e2  07 9e 36 31  34 34 20 ab  20 43 4f 44   ......6144 . cod
>C:0810  45 3a 20 50  52 4f 46 49  31 00 00 10  10 10 10 10   e: profi1.......

so after LOAD, the interpreter hangs when trying to relink the BASIC stub

The same thing will happen on a C64 of course :)

If you quickly go into the monitor while the program is still being loaded and then add the missing zero

> 081b 0

then it will work :)

[radius75]

I can't run this file on a real C64C the normal way.

In Vice, I can run it using the "Inject into RAM" active option. Drag and Drop.
In Ultimate2+, I can run it on a real C64 using the DMA Load option.

--
I didn't notice your explanation @gpz :)

[Felice Nardella]

Thank you for the detailed explanation.
Now it’s clear that the issue is not caused by VICE but by a bug in the PRG generated by Larry’s FLI Converter v187, where the BASIC stub is missing a zero at $081B.
That explains why newer versions of the converter work fine. I’ll try fixing the file manually as you suggested. Thanks again for clarifying this.