?DD ERROR
Tandy / Radio Shack TRS-80
Severity: ModerateWhat Does This Error Mean?
?DD ERROR means TRSDOS encountered a disk drive error — the drive could not read or write to the floppy disk. The disk may be damaged, the drive head may be dirty, or the disk is not formatted for TRSDOS.
Affected Models
- TRS-80 Model I (with disk)
- TRS-80 Model II
- TRS-80 Model III
- TRS-80 Model 4
Common Causes
- Floppy disk damaged or worn
- Drive head dirty from oxide buildup
- Disk not formatted for TRSDOS
- Wrong disk format (single density vs double density)
- Drive belt worn or slipping
How to Fix It
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Try a different floppy disk.
If another disk works, the original is damaged.
-
Clean the drive head.
Use a head cleaning disk with isopropyl alcohol. For 8-inch drives (Model II), use an 8-inch cleaning disk.
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Make sure the disk is formatted for your TRS-80 model.
Model I uses single density. Model III/4 use double density. A Model I disk will not read in a Model III and vice versa (usually).
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Check the drive belt.
TRS-80 drives use rubber belts that perish over decades. A slipping belt causes read/write errors.
Frequently Asked Questions
What size floppies does the TRS-80 use?
Model I and III: 5.25-inch floppies. Model II: 8-inch floppies (massive!). Model 4: 5.25-inch.
Can I use a modern solution instead of floppies?
Yes. Devices like the FreHD (hard drive emulator) or GoTEK (floppy emulator) replace the floppy drive with modern storage. They load disk images from SD cards or USB drives.