Columbia was a file compression utility written by ChaRleyTroniC.
Unlike most other AMSDOS 'crunchers', Columbia's strength was in compressing data and multi-file archives, rather than single executable files. As from version 1.2, several files could be compressed together into one .MRC (Multi-Record Columbia) file. In this respect, it was more like the many compression and decompression utilities available under CP/M. It was written for the Amstrad Action covertape ('Action Pack' 48, issue ???) rather than for the 'scene', something that was reflected in its feature set.
The executable option was rarely used, though one example is TOGETHER.BIN - a runnable archive of the 'Lets get it together' thread from comp.sys.amstrad.8bit, included on side 2 of BTL 4. Screen memory would typically be used for the decompression.
Decrunching source was released with the program. Columbia was slow to decompress compared with other AMSDOS crunchers, though faster to compress than (say) Crown's Crunch or Turbo Imploder. Like Cheese, it used an LZW algorithm.