Re: [TUHS] PL/I stuff - was: Book Recommendation

The vintage computer community has considerable experience with old tapes; in fact Chuck Guzis has a business reading them (which often includes converting old file formats to something modern software can grok). We originally depended heavily on the work of the vintage audio community, who pioneered working with old tapes, including the discovert of 'baking' them to improve their mechanical playability. ("the binder used to adhere the magnetic material to the backing ... becomes unstable" - playing such a tape will transfer much of the magnetic material to the head, destroying the tape's contents.) It's amazing how bad a tape can be, and still be readable. I had a couple of dump tapes of the CSR PWB1 machine at MIT, which I had thoughtlessly stored in my (at one period damp) basement, and they were covered in mold - and not just on the edges! Chuck had to build a special fixture to clean off the mold, but we read most of the first tape. (I had thoughtfully ade a second copy, which read perfectly.) Then I had to work out what the format was - it turned out that even though the machine had a V6 filesystem, my tape was a 'dd' of a BSD4.1c filesystem (for reasons I eventually worked out, but won't bore you all with). Dave Bridgham managed to mount that under Linux, and transform it into a TAR file. That was the source of many old treasures, including the V6 NCP UNIX. Noel