LGP-21 DevKit

VS Code language extension for the LGP-21 drum-memory computer (1963). Provides a full language server for .lgp21 assembly source files, including a compiler

Features

Syntax Highlighting

Tokens are coloured by category: instructions, directives, labels, addresses, string literals, comments, and numeric literals

Diagnostics

Real-time error detection for:

• Duplicate label definitions
• References to undefined labels
• Invalid instruction operands
• Malformed .ORG / .DATA directives
• Unknown string escape sequences
• Invalid numeric/string literals
• Warnings on potential, but not fatal, mistakes

Hover Documentation

Hover over any token for inline documentation:

• Instructions — description and operand format from the 1963 LGP-21 Programming Manual
• Directives — .ORG, .SWITCH, .Q and .DATA usage notes
• Addresses — ttSS address decoding (track and sector) when used as an instruction or .ORG operand
• String escapes — {tf}, {uc}, {lc}, {cs}, {cr}, {bs}, {tb} typewriter control codes

Navigation

• Go to Definition — jump to a label's definition
• Find All References — list every use of a label
• Rename Symbol — safely rename a label and all its references across the file

Document Outline

Open the Outline panel to see all labels in the file as a navigable symbol tree

Auto format source code

Auto foramtting is enabled for lgp21 files. The formatter align labels, instructions and comments for readibility

Commands

• LGP-21: Open Programming Manual - opens the original programming manual as PDF in the OS's default viewer
• LGP-21: Open Example - enables to open one of the embedded example files

Language Reference

String Escapes (inside .DATA strings)

Compiler

Compile the active .lgp21 file. The compiler validates the source and, if there are no errors, writes four output files alongside the source:

The compiler provides warnings and errors the way as the real-time diagnostic does.

Features

• While programmer can use explicit {uc}/{lc} escapes the compiler will automatically apply them based on the character to print, if none provided
• Build command (default to Ctrl+Shift+B) is active only if lgp21 file is opened, but that case it is the default - no task selection needed
• Numeric literals will accept a q value in the form of @q at the end of the literal (for convenience default q value can be set using .Q directive). About the q value read more in the Programming Manual
• Code can add literal index to labels in the form of array like syntax - label[4]

Requirements

VS Code 1.120 or later.