So if I'm running a full node on Bitcoin ABC, where can I find the file or files which contain the blockchain when it is being downloaded? The folder in Program Files is too small, I think, to contain the blockchain.
As per the documentation https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/doc/files.md
blocks/blk000??.dat: block data (custom, 128 MiB per file); since 0.8.0
These files should be in
C:/Users/(username)/AppData/Roaming/Bitcoin which is the standard app data directory.