Spark

File Format
Name	Spark
Ontology	Electronic File Formats Archiving Spark
Extension(s)	.spk, .arc

Spark (Acorn Spark compressed archive) is a type of compressed file archive traditionally found on RISC OS systems, with file type DDC (Archive). Created by SparkFS, these archives were often used to transfer data in a form that could be unpacked by the freely redistributable SparkPlug tool.

Format details

The format is an incompatible variant of ARC. The most obvious differences from ARC are that the high bit of the compression method byte is set, and the member file header has an additional 12 bytes, for RISC OS file attributes. Subdirectories are possible, in a way, by storing them as nested Spark archives.

Software

• nspark - a tool to catalogue and unpack Spark archives (in source code form)
• nomarch v1.3+ can unpack Spark archives.
• [1], [2] → Spark, SparkPlug

Sample files

• Many of the files at The Arcade BBS Filebase (ftp)
  • E.g. Sprite Picture files → level1