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RE: Old PDP11 Tapes

At 04:10 PM 8/30/1999 -0400, Bob & Cecelia wrote:
> ...
>The second step would be to actually read the tape image files under RSTS.
>Hopefully you remember how the tapes were made. I am especially foggy when it
>comes to all of the backup programs that we had on Delta.

If the tapes were created by DEC's BACKUP or PIP programs, those are included with the simulator. Once you've copied the tapes into a file that the simulator can access, then you should be able to simply read them directly. (This assumes that the tapes were originally created under RSTS V7 or earlier.)

Most of Delta's tapes were created with a homebrew program called FAILSAFE. If we ever got to the point of being able to copy Delta tapes into a simulator file, I think I have a hardcopy of the source code of FAILSAFE somewhere that could be used to decipher the file format.

If all else fails, assuming that what the tapes contain is ASCII source code and documentation (i.e. not compiled programs), once you've got them copied into a disk file you might just be able to read them by brute force using an ordinary text editor (maybe even Windows Notepad) and stripping out the garbage between files by hand.

FYI, some friends recently discovered a reel-to-reel audiotape I made in college that had been stored in a non-climate-controlled basement for 15 years. Parts of it were "readable" and parts were not. After 15 years the oxide starts coming off the plastic tape. This was reasonably high-quality audiotape, but I don't know how it compares to computer tape in terms of robustness.