Talk:DECtape

message: I'm skeptical of the claim that DEC's US patent 3,387,293 on DECtape was invalidated. 
The Patent was invalidated. A company in Maryland I believe, whose name escapes me, began making a clone and DEC sued. It was discovered DEC had provided several machines for beta testing, which was commonly done. However, they made an arrangement to sell the machine(s) to one of the beta customers. The receipt for the sale was provided as part of the discovery phase of the suit to the company that had cloned the DECtape machines. DEC had not filed for patent protection until after the beta testing was complete. The sale before the patent application invalidated the patent.
The patent covers aspects of DECtape that are nontrivially distinct from LINCtape.  For instance, LINCtape was designed for bidirectional search, but DECtape was designed for bidirectional data transfer as well.  This required a substantial change to the way the mark track was encoded.
Google doesn't seem to have any other references to this patent being invalidated.  Does anyone have a citation to the court case, or at least know who the plaintiff was?  If not, I think it should be removed from this page and the LINC page.  --Brouhaha 00:44, 19 Oct 2004 (UTC)
replies: text: No citation for the patent being invalidated has been forthcoming in almost two years, so I'm removing that claim.  I also plan to reword the paragraph comparing LINCtape and DECtape, as it is far too POV at the moment.  There were legitimate reasons for some of the major differences between the two, and the patent covers those differences.  --Brouhaha 23:33, 25 August 2006 (UTC)
replies: text:  Apparently the PTO struck a reissue application by DEC on a finding of fraud in the application, and a district court upheld that.  The appeals court ruling (653 F.2d 701) vacated the district court ruling and remanded with instructions for the district court to remand to the PTO.  I haven't yet found anything regarding the eventual disposition.  --Brouhaha (talk) 18:29, 17 April 2011 (UTC)
thread_title:  Patent invalidated? 

message: The blocksize is 129 12-bit words in PDP-8 format, and 256 18-bit words otherwise.  The TU55 book on Bitsavers  says the tape capacity (260 feet of tape) is 4096 blocks in PDP-8 format, which is 6.34 megabits.  The number of blocks in the other format (PDP10/11/15 format) is 578, which translates to 2.66 megabits.  This doesn't make sense.  I'm positive about the 10/11/15 capacity, but the other comes from a DEC manual...  did the length of the tape change?  Paul Koning 20:56, 9 April 2007 (UTC)
thread_title:  Tape capacity? 

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thread_title:  External links modified 

message: There are many references in the article to the format being reasonably quick (certainly compared to paper tape, anyway) and usable like a slow disc drive in practice. But actually how fast was it? There's no mention anywhere. Presumably it may take a few seconds to seek through the whole tape looking for a particular block out of the ~512 (for 18-bit records/blocks) total (using simpler, broader marks on one of the tracks that could be counted off at high speed), and then another half second or so to read that actual block? (=512 words/sec raw read rate, a little less sustained when reading blocks sequentially without any further seeking, merely waiting out the small gaps between them, and rather less for full random access). That would be a significant improvement over the ~60cps (or ~20wps) of paper tape, but still grant an worthwhile advantage to a more costly drum memory or extremely expensive early hard disc system (a few dozen kwords/sec)... However, that's just an educated guess based off how tape drives appear to behave in footage of their use (rapid, jerky movements when performing actual reads/writes with maybe a couple of spurts per second, and very rapid seeking back/forth in between any sequential R/W), and their market position between the better known speeds of those other devices, so does anyone have actual information? 146.199.0.175 (talk) 15:37, 20 March 2018 (UTC)
thread_title:  Read/write speed? 

message: I saw the sizes in "inches" information for the incompatible LINC tapes, but not for this tape. Did it come in 10" (10 inches) and/or other sizes? Misty MH (talk) 19:18, 1 December 2022 (UTC)
thread_title:  DECtape SIZE is not mentioned by "inches"