ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³ MEMORY RECOVERY ³ ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´ ³ What When & How ³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ In case you've ever wondered what answering YES to the dreaded "Try To Recover Memory?" prompt does exactly, no wonder. The information is hard to find. Don't look for the answer in the "Owner's Manual" for the HP48 S/SX, which states merely, "You can also answer YES to the 'Try To Recover Memory?' prompt -- however, the calculator may not be able to recover all memory at that point. You probably would lose at least your stack, alarms, and user-key assignments." Pretty vague. The "User's Guide" for the HP48 G/GX is even more cryptic: "Press YES if you want to try and recover the variables you have stored in HOME and in Port 0. There is no guarantee that all the variables can be recovered." Which, when, and how? Undocumented. The information is available in Bill Wickes' book, "HP 48 Insights", but that's not freely available. The actual procedure that the HP48 uses for memory recovery has been in only one document from HP: the June 1991 issue of the Hewlett Packard Journal, which contained an article by Bill Wickes and Charlie Patton entitled "The HP 48SX Scientific Expandable Calculator: Innovation and Evolution". Buried in that article (copyright (c) 1991, Hewlett Packard Company, excerpt reprinted here with permission of the Hewlett Packard Company) were the following paragraphs that explicitate the memory recovery procedure: If the user chooses to salvage data, the machine first searches through RAM, locating library or backup objects whose checksums are valid. It collects all of these into a new port 0. It then searches for a directory object having the specific features of the home directory. If one is found, the RAM recovery operation verifies its structural integrity, and the operation is complete. To check the directory's structural integrity, the RAM recovery operation checks the structural integrity of each object within the directory (including recursively checking subdirectories) and removes any that are corrupt. If no home directory is found, the RAM recovery operation begins searching for ordinary directory objects. When it finds a directory it checks the structural integrity of each object within the directory (including recursively checking subdirectories) and removes any that are corrupt. The resulting corrected directories are named D.01, D.02, and so on, and are gathered together to form a new home directory, completing the recovery process. Thanks to Bill and Charlie for writing this up. -jkh-