Tsugaru_QT 1.1.0 tidies up mouse capture for the FM Towns emulator on Linux

A new Qt frontend release for the FM Towns and Marty emulator Tsugaru overhauls mouse integration and adds disc profiles, aimed at making the obscure Japanese platform usable on Linux.

AI-drafted from 2 sources. This story was written with AI from the outside reporting listed under Sources, and checked by automated tools before it went up. The originals have the full detail.

A Qt-based frontend for the FM Towns and Marty emulator Tsugaru has shipped version 1.1.0, and the headline change is something most emulators solved years ago: getting the mouse to behave.

FM Towns was Fujitsu's early-90s hybrid of a PC and a CD-ROM console, built for Japanese multimedia titles that needed more storage than a floppy could give. Marty was the console-only spin-off. Both are niche even by retro-computing standards, which is presumably why the underlying emulator, Tsugaru, written by a developer known as CaptainYS, has mostly lived as a command-line tool. Tsugaru_QT, built by a separate maintainer on GitHub under the handle 3d4m0t0, wraps that core in a proper Qt 6 interface with menus, settings dialogues and the usual conveniences a command-line emulator lacks.

Why mouse capture was a problem

According to the project's release notes, FM Towns software expects the guest operating system to know exactly where the pointer is, and previous versions of the frontend struggled to keep that mapping stable once the host environment changed, for instance after a CMOS reset. The fix in 1.1.0 is to give app-specific mouse integration an offset based on something called DS.base, a memory reference point inside the guest, so the pointer mapping survives environment changes rather than drifting or breaking outright. The notes also say the maintainer has simplified the control options down to two modes, Default and Mouse capture, with Default falling back through app-specific integration, then the Mouse BIOS, then capture, in that order. A middle-click now switches to capture mode even while app-specific or BIOS integration is active, which sounds like a small thing until you have tried to wrestle a pointer back from an uncooperative emulator mid-session.

None of this is flashy, but it is the kind of detail that decides whether an emulator is something you tolerate or something you actually use for an afternoon of FM Towns adventure games, most of which lean heavily on point-and-click input.

What else changed

The release notes list a longer set of changes beyond input handling. Disc profiles now save settings per mounted CD, including floppy and hard disk mount state and the mouse integration settings themselves, so quitting and relaunching with the same disc restores where you left off. There is a new auto-resume feature that saves emulator state on exit when a disc profile is active, and reloads it on next launch. Hard disk images are now created sparse by default, matching upstream Tsugaru's behaviour, meaning an empty drive image takes up little space on disk until data is actually written to it, with an option to convert older dense-format images using a Compact tool. CD image support has been extended to include the .chd format, a compressed disc image container more commonly associated with MAME. The changelog also mentions reworked timing so that emulated VSYNC and audio tempo stay steadier, and separate CPU timing tables that emulate i386-era instruction speed distinct from the i486 core, intended to bring the emulator's Compatible mode closer to how real FM Towns hardware behaved.

What is still unclear

The release notes are the only detailed source available, alongside a discussion thread on r/emulation, and neither offers independent testing or benchmarks, so how the mouse fix performs in practice, and whether the timing changes measurably improve accuracy against real hardware, is not something reported here. The project's own documentation also discloses that some code was generated with an AI-assisted IDE and reviewed by the maintainer, which is worth knowing if you are auditing the source. For a platform this obscure, incremental fixes like these are unlikely to make headlines elsewhere, but for anyone trying to run FM Towns software on Linux, getting the pointer to behave is the difference between a working emulator and a frustrating one.

Sources

Image: Illustration: AI-generated for Gaming World