TOS Error -39
Atari Atari ST
Severity: ModerateWhat Does This Error Mean?
TOS Error -39 means the system does not have enough free memory to complete the operation. Close other applications, reduce desk accessories, or add more RAM. The 520ST with only 512KB is especially prone to this error.
Affected Models
- Atari 520ST
- Atari 1040ST
- Atari STe
- Atari TT030
- Atari Falcon030
- Hatari emulator
Common Causes
- Not enough free RAM to run the application
- Too many desk accessories loaded
- Multiple programs running simultaneously (with a multitasking extension)
- Large file or image requiring more memory than available
- Only 512KB RAM on a 520ST — insufficient for many applications
How to Fix It
-
Close other running programs and desk accessories.
Under the Desk menu, close any open accessories. Quit any running applications to free their memory.
-
Remove unnecessary desk accessories from the AUTO folder.
Desk accessories (.ACC files) load at startup and stay in memory. Move unused .ACC files out of the root directory to prevent them loading.
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On Hatari emulator: increase the RAM setting.
Go to System settings and increase RAM to 4MB or more. This gives the emulated ST far more memory than the original hardware.
-
Upgrade from 520ST to 1040ST RAM (or use a RAM expansion).
The 520ST has only 512KB — many applications need more. The 1040ST has 1MB. Some 520STs can be upgraded to 1MB with a soldering modification.
Frequently Asked Questions
How much RAM does the Atari ST have?
The 520ST has 512KB, the 1040ST has 1MB, the STe has 1MB (expandable to 4MB), and the Falcon030 has 4MB (expandable to 14MB). The TT030 supports up to 26MB of RAM.
Can I add more RAM to an Atari ST?
The 520ST can be upgraded to 1MB, 2.5MB, or 4MB with internal modifications. The STe has SIMM slots for easy expansion up to 4MB. The Falcon030 and TT030 also support RAM expansion.