These files were restored from Andrew McKendrick's paper tapes. They are mostly of the KDF-9 Imp compiler, which was written in Imp (which was much closer to Atlas Autocode back then) but with much embedded assembly code. Note that 'IMP9 compiler tape 1 imp' uses %CAPTION to print text messages, which is pure Atlas Autocode. Whereas 'IMP PS Program' uses %PRINTTEXT which was the early Imp equivalent. (Later Imp programs used a string procedure "Print string()", but this was before David Rees had added strings to the language). Also variables such as "N'" in "N=0 ; N'=0" are classic Atlas Autocode. There is very little in this that is specifically Imp - in fact I am beginning to suspect that this is the very first Imp compiler which is in the process of being bootstrapped through Atlas Autocode, and that the earlier compilers (such as for the Atlas itself) were actually AA compilers even though we may have started called them "Imp" at Edinburgh. This is the oldest Imp compiler known to still exist. We have not located any copies of the Atlas Autocode compilers, although we do have the Atlas Autocode manual, which will come in useful later as it describes the character set encoding used on the Atlas. The .asc files have had the parity bit stripped coming off the paper tape reader, and NULs removed. The .bin files are untouched. The file names are what was written on the paper tape. These files were restored by a Herculean effort from Ian Young and Chris Whitfield which is documented elsewhere.