TIImageTool - sometimes also called TIMT by me - is a Java-based tool for easy working with disk images that are used by many emulators, notably MAME. Disk images are files that hold the complete contents of a floppy or hard disk in terms of sector contents; they are not archive files. In the simplest way, a disk image is a sequence of the sector contents from 0 to 359 for a SSSD disk, or more, depending on the format.
I designed and developed TIMT since 2011 as an alternative to the command line tool imgtool that is part of MAME. This tool is used to create and change disk images. However, working with the command line tool proves to be quite limited, since it contains mainly those operations that work across different emulated platforms, and there are so much more things that could be helpful.
TIMT is written in pure Java, which is the probably best choice, because it should run on all platforms that MAME is also running on (at least Linux, Windows, Mac). That is a good point for Java.
In recent times, people start to get suspicious about Java and call it a "security thread". These concerns only apply to Java applets (which are executed inside a browser window). TIImageTool is not run from a browser, it is locally installed. Like every locally installed application, it runs with all privileges of the user who started it.
However, when you install a Java Runtime Environment you should make sure that Java support in your browser is not unexpectedly turned on. Start your browser (Firefox, IE, whatever) and make sure that the "Java support" in the browser extensions/plugins is deactivated.
TIImageTool is also available from WHTech. Note that you need a Java Runtime Environment version 7 or higher. The Java RE can be downloaded from https://www.java.com/download/ or from http://openjdk.java.net/.
Since July 2016, TIImageTool source code is available from Github: https://github.com/mizapf/tiimagetool
2.4: Sector editor; i18n, l10n for English, German; CF7 handling
2.3: HFE (Lotharek) image support; Search function
2.2: Sources available on Github; changed package structure; removed "Open device"
2.1: Open recent files; enhanced filesystem check; some fixes; output redirect
2.0: Drag-and-drop support; detachable views; paste BASIC into image
1.5: Image display (TI ARTIST, MyArt, YAPP); GPL disassembler; Tagged Object Code disassembler
1.4: Full CHD support (creating, extracting, importing, converting), Archiver support; Geneve boot disk creation
1.3: Imports binary content as a PRG file and reads TI99-PC SDF images with appended bad sector list
1.2: External device handling (working with Compact Flash or external drives). Known issue: In Windows you cannot write to the CF/external drive.
1.1: Supports CHD version 5 (MESS 0.145)
1.0: Initial version