ARC to TAR.7Z (T7Z) Converter

ARC is one of the earliest widely-used compressed archive formats for personal computers, created by Thom Henderson of System Enhancement Associates (SEA) in 1985 for MS-DOS. The format combines multiple files into a single archive with per-file compression, supporting several compression methods including no compression (stored), run-length encoding, Huffman coding, and LZW (Lempel-Ziv-Welch) variants. Each file entry in an ARC archive carries its own header with the original filename, compressed and uncompressed sizes, timestamp, CRC checksum, and compression method indicator. ARC became the dominant archive format on DOS-based bulletin board systems (BBS) during the mid-1980s, serving as the primary means of distributing software, documents, and data files online before the internet era. The format sparked a notable legal controversy when Phil Katz created a compatible utility (PKARC), leading to a lawsuit from SEA that ultimately motivated Katz to develop the ZIP format as a legal alternative. One advantage of ARC was its per-file compression approach, allowing individual files to be extracted without decompressing the entire archive. The integrated CRC checksums provided another benefit, enabling reliable verification of data integrity after transfer over error-prone modem connections. While ZIP and more modern formats supplanted ARC by the early 1990s, the format holds historical significance as a foundational technology in the evolution of data compression and file distribution.