I have excerpted the write-up from the DECUS Program Library Addendum No. 1. There seem to be a couple of typos in there, which are corrected in the files toggle.{pal,lst,bin}. The ERC loader is a predecessor of, and similar to the HELP loader DEC-08-LHAA. Instructions are coded at the head of the tape to be loaded into memory with a minimum of hand toggling. Those instructions form a stripped down loader similar to the BIN loader, but without checksum, which is used to load the last page with a memory clear, a RIM loader, and a BIN loader (which does not handle extended memory). The cleaned up tape image is in decus-5-27.erc. The original tape image, decus-5-27.bad, has a corrupted word in the RIM loader. I have also disassembled and annotated the last page in lastpage.{pal,lst,bin}. The file lastpage.bad shows the corrupted RIM loader. The file tape.txt attempts to explain the boot process in terms of what is deposited when as the tape is read. Vince