---
title: "Sinclair BASICs: DEF FN"
type: "article"
slug: "sinclair-basics-def-fn"
url: "http://localhost/article/sinclair-basics-def-fn/"
markdown_url: "http://localhost/article/sinclair-basics-def-fn.md"
published_at: "2025-07-12T01:55:09+00:00"
modified_at: "2025-07-12T01:55:10+00:00"
featured_image:
  url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg"
excerpt: "This is a look at the DEF FN keyword of Sinclair BASIC and its companion function FN because it was a feature I used very little, and that I recently dug into and found some surprises."
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  - name: "TS 2068"
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issue: "12"
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  - id: 60034
    title: "ZXzine Issue 12"
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pages: "15-19"
pubdate: "July 2025"
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---

# Sinclair BASICs: DEF FN

This is a look at the DEF FN keyword of Sinclair BASIC and its companion function FN because it was a feature I used very little, and that I recently dug into and found some surprises.