At MIT's Artificial Intelligence (AI) Lab and Laboratory for Computer Science (LCS), we have rooms full of 7-track and 9-track magnetic tapes in various states of decay. These tapes are the incremental, full, and archival dumps of all the machines used for everyday work by students, faculty, and staff in the Labs from 1971 to 1990. The data on any individual tape may or may not be valuable; we are unable to tell. Much of this data was written by operating systems no longer in common use, such as ITS, TOPS-20, and Genera. An air conditioner malfunction has allowed water to leak onto some of the tapes. Some of the protective outer tape rings have grown old and brittle. Many have already failed, causing the tape to fall off the tape racks and their cases to shatter. Many tapes are being stored off-site in an environmentally controlled warehouse, but some are completely un-cataloged. Others may be sitting lost in the lab's basement somewhere. Furthermore, we are losing the knowledge required to make sense of the data on the tapes, which could be in one of a dozen formats. Even perfectly preserved tapes may thus soon be reduced to gibberish. We need to pay attention to more than just the tapes themselves; we need to rescue data from the operators who wrote these tapes and from the paper dump logs. In summary, we are losing irreplaceable data every day.
Operating System | Machine | Density (bpi) | Format | Approximate Year Written | Number | Size | |
---|---|---|---|---|---|---|---|
ITS | DM KA-10 | 800 | 9 track | 1976--83 | 330 | -- | |
ITS | AI KA-10 | 800 | 7 track | 1971--82 | 362 | -- | |
ITS | ML KA-10 | 800 | 7 track | 1973--83 | 203 | -- | |
ITS | MC KL-10 | 800 | 7 track | 1976--85 | 511 | -- | |
ITS | MC KL-10 | 1600 | 9 track | 1981--86 | 60 | -- | |
ITS | All KS | 6250 | 9 track | 1985--90 | 159 | -- | |
ITS Total | 1625 | 77GB | |||||
Tops-20 | AI OZ | 1600 | 9 track | 1982--86 | 397 | -- | |
Tops-20 | AI OZ | 6250 | 9 track | 1986--88 | 118 | -- | |
Tops-20 | LCS XX | mixed | 9 track | 1976--88 | 423 (in storage) | -- | |
Tops-20 Total | 938 | 132GB | |||||
Mixed/Unspecified | 1600 | 9 track | -- | 757 | 30GB | ||
Mixed/Unspecified | 6250 | 9 track | -- | 436 | 63GB | ||
Grand Total | 3,756 | 302GB |
The long-term goal of this project is to provide a usable system whereby users can easily search and access all the Labs' archival data in a uniform fashion, and to preserve this data in such a manner that it can be decoded even if all the supporting documentation for it is lost. The more immediate goal is to assemble the incremental, full, and archival backups from the Incompatible Timeshare System (ITS), record them on new media in a long-term (archival) format suitable for use well into the future, and provide tools to help search and manage this large data set in an effective manner. The entire collection of readable ITS backup tapes contains approximately 77 gigabytes of data, and constitutes our smallest collection of tapes. Table provides a brief breakdown of the tapes that have been accounted for and are believed to contain useful data. There are other tapes around the lab which are unlabeled, and there are many tapes known to be uninteresting ``scratch'' tapes.
Starting in 1968, ITS was the workhorse of Project MAC, which later
divided into the Laboratory for Computer Science (LCS) and the
Artificial Intelligence (AI) Lab. ITS ran on a two hardware
platforms, the DEC PDP-6 and later the PDP-10; and was implemented
entirely in MIDAS, an assembly language with macro
facilities
There has been a demonstrated need for some of the data on these tapes. We are not just trying to rescue data that will never be used. Here are some examples of requests that we have encountered: