an 8mm camera or player cannot keep track of where the tape is during fast forward and rewind (though it could during shuttle search). This made editing using a linear editing system problematic. Some later cameras and players attempted to derive the tape position from the differential rotation of the spools with limited success. Tape and recording protection As with many other video cassette formats, 8mm videocassettes have a tape-protecting mechanism built into the shell. Unlike the ones on VHS and VHS-C shells, which consist of only a single piece of plastic that protects the part of the tape that is read by the player/recorder, Hi8's tape-protection mechanism consists of two pieces of plastic at the top of the shell that come together and form a casing that protects both sides of the tape, and a latch that prevents this casing from opening and exposing the tape. The playback/recording unit can depress this latch to open the casing and gain access to the tape. To prevent the recording on the tape from being erased, there is a small write-protect tab that can be moved to one of two positions, labeled "REC" and "SAVE" (sometimes marked as "ERASE ON" and "OFF", respectively). Comparing the sliding tab to a door, the tape is in the "REC" position when the "door" is open and in the "SAVE" position when it is closed. (Not all tape cases have markings for this information.) The tape can only be recorded onto (or recorded over) when this tab is in the "REC" position. This is an improved version of the VHS write-protect tab, which prevents erasure after it has been broken off, requiring covering with adhesive tape or filling with an obstruction to remove the write protection. Non-camcorder use Home market Efforts were made to expand Video8 from only the camcorder market into mainstream home video. But as a replacement for full-size VCRs, Video8 failed. It lacks the long (5+ hours) recording times of both VHS and Betamax, offers no clear audio/video improvement, and cost more than equivalent full-size VCRs. Even with all of the advanced features offered in high-end Video8 machines, there was no compelling reason to switch to Video8 for the home application. Initially, many movies were prerecorded in 8mm format for home and rental use, but the rental market for Video8 never materialized. Sony maintained a line of Video8 home VCRs well into the