It turned out to be a bug in WUTIL 3.2. The boot loader is one byte too short. $90 NOP must be present twice. One byte is discarded by the BIOS, see :08a0.
Now i have Windows 1.0.3 running, and i would like to use a microsoft serial mouse (which seems supported in 1.0.3).
Do i have to add additional code? Guess i have to wire some signals. There aren't that many samples in our repository (the PC JR uses another UART)...
(WineMine ported to Windows 1.x by Nathan Lineback)https://www.dropbox.com/s/0isjzpfwlbddpaj/MS_Windows_1.0X_1985_SCREENSHOT_WineMine.png?dl=0