Msg: 5175 *Conference*
07-06-94 17:28:35
From: TRACY ALLEN
To : COMET _
Subj: REPLY TO MSG #5163 (UNDELETE -- COLD START RECOVERY)
That "impossible" was an unfortunate choice of words. You have pointed out that nothing is impossible! There are some kinds of "events" that can indeed scramble everything in memory. But truly, if the recovery routine can get back the .DO files, a more sophisicated routine could just as well recover both .BAs and .DOs. "More sophisticated" is the watchword here. There are some programs of that type that have been available through the years, but without something like the XR4 to store them in, you had to find a cassette tape and load in the recovery program. If you had a cassette tape, you had backups of everything anyway, right? If you cold start your computer, the first three bytes in RAM at 32768 to 32770 will be zeros, and then a 26, and the rest of RAM will be just as it was before the cold start. Well, there are changes to the system directory too and to the system pointers. But since BASIC programs end with the 000 string and the .DO files end with a 26 (^Z), you could write a program to scan for "000" and assume that each 000 marks the end of a BASIC program, and update the file directory as such. I believe that the ^Z character does not normally occur in BASIC programs, so you might be able to assume that when an ^Z is found, you have passed the end of the last BASIC program and have just located the end of the first .DO file, and update the directory appropriately. I can see ;you are going to have lots of fun!