---
title: "Keyboard Scanning from Machine Code"
type: "article"
slug: "keyboard-scanning-from-machine-code"
url: "http://localhost/article/keyboard-scanning-from-machine-code/"
markdown_url: "http://localhost/article/keyboard-scanning-from-machine-code.md"
published_at: "2026-03-13T00:25:47+00:00"
modified_at: "2026-03-13T00:25:48+00:00"
featured_image:
  url: "http://localhost/wp-content/uploads/2022/04/20230809-041332.jpg"
excerpt: "Explains how to scan the ZX80/81 keyboard from machine code in SLOW mode using the LAST K system variable (16421-16422). Covers key-value demonstration, FAST/SLOW mode selection from machine code using ROM addresses, and presents a complete machine code keyboard scanning routine that mirrors Sinclair's own BASIC keyboard feel."
category:
  - name: "Syntax"
    slug: "syntax"
    taxonomy: "category"
    url: "http://localhost/category/periodicals/syntax/"
post_tag:
  - name: "Machine language programming"
    slug: "machine-language"
    taxonomy: "post_tag"
    url: "http://localhost/tag/machine-language/"
  - name: "TS 1000"
    slug: "ts1000"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts1000/"
  - name: "ZX80"
    slug: "zx80"
    taxonomy: "post_tag"
    url: "http://localhost/tag/zx80/"
model:
  - name: "Sinclair ZX80"
    slug: "zx80"
    taxonomy: "model"
    url: "http://localhost/model/zx80/"
  - name: "Timex/Sinclair 1000"
    slug: "ts-1000"
    taxonomy: "model"
    url: "http://localhost/model/ts-1000/"
indiv:
  - name: "Ian Logan"
    slug: "ian-logan"
    taxonomy: "indiv"
    url: "http://localhost/indiv/ian-logan/"
publication_r:
  id: 10246
  title: "Syntax"
  type: "periodical"
  url: "http://localhost/periodical/syntax/"
authors_r:
  - name: "Ian Logan"
    slug: "ian-logan"
    taxonomy: "indiv"
    url: "http://localhost/indiv/ian-logan/"
volume: "3"
issue: "7"
issues_articles:
  - id: 52481
    title: "Syntax/Syntax ZX80 v3 n7"
    type: "issue"
    url: "http://localhost/issue/syntax-syntax-zx80-v3-n7/"
pages: "6"
pubdate: "July 1982"
archive_link: false
---

# Keyboard Scanning from Machine Code

Explains how to scan the ZX80/81 keyboard from machine code in SLOW mode using the LAST K system variable (16421-16422). Covers key-value demonstration, FAST/SLOW mode selection from machine code using ROM addresses, and presents a complete machine code keyboard scanning routine that mirrors Sinclair’s own BASIC keyboard feel.