Okay, let's see. The user is reporting that QEMU freezes when running MS-DOS with EMM386.EXE and the HIGHSCAN option. They've tried versions 0.11.2 and 0.14.0 on Ubuntu 10.04 with a 486 CPU and 16MB RAM. Without the HIGHSCAN switch, it works but their software doesn't function. First, I need to categorize this bug. The possible categories include things like mistranslation, assembly issues, device problems, network, etc. The user mentioned that when they added traces in `default_ioport_read`, there were accesses to certain DMA registers and ports. They expected some access to F000h-F7FFh but didn't see it. This suggests an issue with how the I/O ports are being handled by QEMU, possibly related to EMM386's HIGHSCAN feature. EMM386 manages extended memory under DOS, and when using HIGHSCAN, it might be trying to access higher memory regions that QEMU isn't handling correctly. The freezing indicates a hang, which could mean an infinite loop or an unhandled interrupt. Looking at the traces, there are repeated inb/outb operations on specific ports (0x87, 0xc4, etc.), which might be related to the EMM386's interaction with hardware or how QEMU emulates it. Since this is happening during I/O port accesses, the issue likely lies within QEMU's emulation of these devices. Given that QEMU relies on accurate device emulation and proper handling of I/O ports, the bug probably falls under 'device' category because it's related to how EMM386 interacts with emulated hardware in QEMU. The bug is related to how QEMU handles specific I/O port accesses when using EMM386.EXE with the HIGHSCAN option. This likely points to an issue in device emulation, particularly with how certain ports are being managed or accessed by the guest OS. **device**