Paul, Very interesting, thanks for sharing. Bill On Thu, Mar 11, 2021 at 7:54 PM Paul Koning via cctalk < cctalk@classiccmp.org> wrote:
> I just read part of the Grant Saviers interview from CHM, where near the > end he gives a bit of history of DECtape. In particular, the fact that it > was derived from LINCtape though the format details are quite different. > > A question popped into my mind, prompted by having read Guy Fedorkow's > paper about Whirlwind just a few days earlier: the Whirlwind tape format > has 6 physical tracks but 3 logical tracks (each logical track is recorded > redundantly on two physical tracks) and one of those tracks is a clock > track. LINCtape and DECtape have the same redundant recording scheme, and > also have a clock track; the difference is that they add a mark track to > enable the recording of block numbers and in-place block writing. > > That made me wonder if LINCtape was, in part, inspired by the Whirlwind > tape system, or if those analogies are just a concidence. > > Incidentally, it's probably not widely known that LINCtape/DECtape is not > the only tape system with random block write capability. Another one that > does this is the Electrologica X1 tape system, which uses 1/2 inch 10 track > tapes, which include a clock and a mark track. An interesting wrinkle is > that the X1 tape system lets you chose the block size when formatting the > tape, and then data block writes allow for the writing of any block size up > to the formatted block size. I'm not sure when that device was introduced; > the documentation I have is from 1964. There's no sign the designers knew > of DECtape (or vice versa). > > paul > >
