the Type 555 transport, with the same interface signals and the same physical tape medium. The LINC and DEC controllers, however, are incompatible, and the positions of the supply and take-up reels were reversed between the LINC and DEC tape formats. While LINCtape supports high-speed bidirectional block search, it only supports actual data read and write operations in the forward direction. DECtape uses a significantly different mark track format to provide for the possibility of read and write operations in either direction, although not all DECtape controllers support reverse read. DEC applied for a patent on the enhanced features incorporated into DECtape in late 1964. It is notable that the inventor listed on this patent, Thomas Stockebrand, is also an author of the paper on the TX-2 tape system from which the LINC tape was derived. Eventually, the TC12-F tape controller on the PDP-12 supported both LINCtape and DECtape on the same transport. As with the earlier LINC-8, the PDP-12 is a PDP-8 augmented with hardware support for the LINC instruction set and associated laboratory peripherals. Technical details DECtape was designed to be reliable and durable enough to be used as the main storage medium for a computer's operating system (OS). It is possible, although slow, to use a DECtape drive to run a small OS such as OS/8 or OS/12. The system would be configured to put temporary swap files on a second DECtape drive, so as to not slow down access to the main drive holding the system programs. Upon its introduction, DECtape was considered a major improvement over hand-loaded paper tapes, which could not be used to support swap files essential for practical timesharing. Early hard disk and drum drives were very expensive, limited in capacity, and notoriously unreliable, so the DECtape was a breakthrough in supporting the first timesharing systems on DEC computers. The legendary PDP-1 at MIT, where early computer hacker culture developed, adopted multiple DECtape drives to support a primitive software sharing community. The hard disk system (when it was working) was considered a "temporary" file storage device used for speed, not to be trusted to hold files for long-term storage. Computer users would keep their own personal work files on DECtapes, as well as software to be shared with others. The design of DECtape and its controllers is quite different from any other type of tape drive or controller at the time. The