If you read it carefully it does not run from the archive, it simply uses patch files, differential backups. Since we know the majority of the file will remain the same its possible to only save the difference from the original. Either by creating a file with offset, run, and data for every change or by performing a difference on all bytes then compressing the outcome (In a worse case scenario either of these could result in the patch being larger than the original, but that's not likely.)CrunchyOS Manual wrote: Writeback for archived programs is implemented by creating and loading small patch files, and archiving those instead of the complete program. This takes up more memory, but the calc will perform garbage collects far less often.
This does not mean running from the archive. Which, excluding the programs that get attached to crunchyOS, isn't possible due to a hardware restriction. You can't execute an archived program. It must be copied to the ram.