?SN ERROR
Tandy / Radio Shack TRS-80
Severity: MinorWhat Does This Error Mean?
?SN ERROR on the TRS-80 means Syntax Error — BASIC could not understand the command you typed. You have misspelled a keyword, used incorrect punctuation, or written a statement that BASIC does not recognise. Type LIST to review the offending line and look for the mistake.
Affected Models
- TRS-80 Model I
- TRS-80 Model II
- TRS-80 Model III
- TRS-80 Model 4
- TRS-80 Color Computer (CoCo)
- MAME TRS-80 emulator
- trs80gp emulator
Common Causes
- Misspelled BASIC keyword (e.g. PIRNT instead of PRINT)
- Missing or misplaced punctuation — commas, semicolons, quotes, or brackets
- Using a keyword from a different BASIC dialect that does not exist on your TRS-80 model
- Variable name that starts with a reserved word
- Typing a Level II BASIC command on a Level I machine (Model I only)
How to Fix It
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Type LIST and press ENTER to see the line that caused the error.
BASIC shows the line number next to the error message. LIST displays the line so you can spot the typo or mistake.
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Check for misspelled keywords — TRS-80 BASIC requires exact spelling.
Common mistakes: PIRNT for PRINT, INPTU for INPUT, GOSUB written as GO SUB. Unlike some BASICs, the TRS-80 does not accept abbreviated keywords in program lines.
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Make sure all quotes are properly paired.
Every opening quote must have a closing quote. PRINT "HELLO is missing its closing quote and causes ?SN ERROR.
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Retype the line from scratch using the line number.
Type the line number followed by the corrected statement and press ENTER. The new version replaces the old one in memory. For example: 10 PRINT "HELLO WORLD"
Frequently Asked Questions
What is the difference between Level I and Level II BASIC on the TRS-80?
Level I BASIC was a very simple BASIC included in the original Model I with 4KB ROM. Level II BASIC (by Microsoft) was much more powerful, adding string handling, multi-character variable names, and more commands. Most TRS-80 software requires Level II.
Why was the TRS-80 nicknamed the Trash-80?
The nickname was affectionate teasing about the TRS-80's build quality and Radio Shack's mass-market reputation. Despite the nickname, the TRS-80 was hugely successful — it outsold the Apple II in its first year and introduced millions of people to personal computing.