This 53 page, pocket-sized reference guide covers the important commands (and their syntax), error codes and the register bitmaps for the various interface cards. The last couple of pages include a ASCII table to convert ASCII characters to Binary or Octal or Hex or Decimal.

The first edition was printed on June 1, 1980. This is the second edition of the reference guide and was printed in September 1980. The difference between this and the first edition is that the second edition carries updated information for the HP 98228A Disk ROM. Just to be neat...HP even gave this pocket reference guide it's own part number. It's Manual Part No. 09825-90012.