What is the TD file format?
A .td file is a configuration file used by Borland Turbo Debugger for DOS. It stores settings for the debugger, which is launched by issuing the TD command from the DOS command line.
Debugging is a process of identifying and removing errors in software programs. A program is run in a special mode - configured in part via a .td file - where the user has control over the execution of source code. In this way the user can locate lines of code that are the sources of errors or faulty execution; the code is executed in steps so the programmer can trace the process and correct found errors.
Borland Turbo Debugger shipped as several executables: TD.EXE for real-mode DOS, TD286.EXE for 286 protected mode, and TD386.EXE for virtual 386 mode (which required the TDH386.SYS device driver). Each could save and reload a .td configuration file, preserving window layout, active breakpoints, watch expressions, and display preferences between sessions.
Turbo Debugger 1.0 shipped in 1988 and reached its final release at version 5.5 in 1996. The Win32 counterpart used the .td2 extension. Borland was later acquired by Embarcadero; Turbo Debugger is no longer actively distributed, but can still be run on modern systems using DOSBox alongside the original TD.EXE executable.
Security & safety
RISK: LOWInert binary settings file from a discontinued DOS debugger. No execution capability; no known malware vector.
Format details
in a nutshell- Tesla Model S/X diagnostics dump - .td extension occasionally appears in Tesla vehicle diagnostic exports - entirely unrelated to Borland.
- Ticker Data file - Some financial data applications use .td for time-series tick data exports.
Programs that open TD files
Windows3 apps
Turbo Debugger
Paid Original application - reads the config on startup. EOL since ~1996; no longer available commercially.
HxD (hex editor)
Free Open in HxD to inspect binary contents - no practical editing use, but useful for identifying the file.
DOSBox (with Turbo Debugger)
Open-source Mount the directory in DOSBox and run TD.EXE - it will read the .td config automatically. 
Linux1 app
DOSBox (with Turbo Debugger)
Open-source Same as Windows DOSBox approach - mount directory, run TD.EXE. Technical details
deep spec| Developer | Borland Software Corporation |
| Application | Borland Turbo Debugger for DOS, versions 1.0 through 5.5 |
| Encoding | Binary, little-endian, proprietary |
| Typical file size | Under 10 KB |
| Stores | Window layout, breakpoints, watch expressions, display options, session preferences |
| Executable variants | TD.EXE (real-mode DOS), TD286.EXE (286 protected mode), TD386.EXE (virtual 386 mode) |
| Required driver | TDH386.SYS required for TD386.EXE virtual 386 mode |
| Win32 counterpart | .td2 (Turbo Debugger for Windows configuration) |
| Platform | MS-DOS; Windows 3.x (via DOS box) |
| Status | Discontinued; Borland acquired by Embarcadero; Turbo Debugger no longer distributed |
| Emulation | Can be run under DOSBox with original Turbo Debugger executables |
| Released | 1988 (Turbo Debugger 1.0 for DOS) |
| Latest version | Turbo Debugger 5.5 (1996, final Borland release) |
Community Q&A
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