To understand the whole CMR problem, we have to turn to another technology that fits perfectly and, in fact, we can say that it was even perplexed. We refer to PMR, a technology that came before and in a very curious way maintained their name even when it ceased to exist.
CMR yes or CMR no, each manufacturer chooses something different
CMR dictionary of General Magnetic Recordings good luck or bad is not understood today without inventing PMR. And do most manufacturers when talking about one technology talk indirectly to another and vice versa.
The problem is, not only in time from a temporal or temporal perspective, but from the fact that, by mistake and without understanding, they are both technologically skipping and each manufacturer chose to name their HDD by one name or another.
PMR is a technique that allows recording of perpendicular magnetic fields on HDD plates, enhancing the density, but at the same time, companies have been working with other technologies that have achieved the same result, but in a completely different way.
With PMR, instead of recording upright tracks, it is done precisely, preserving the visible surface of the plate and thus increasing the sensitivity. CMR, on the other hand, has sought to reduce the write-head so small that a magnetic track can be recorded, which in turn allows for higher density.
Two different ways to achieve one goal
Interestingly, the two technologies are made similarly, as if it were a copyright infringement to see which one was ultimately patented. The end result is where the argument arises that both of these materials were used in both the present and the present times, but this is possible because they were both compatible.
The findings at that time were to record the information vigorously and by looking at the details of the PMR and at the same time reduce the headset to be smaller than that of the recorded track.
The problem is that the PMR has left the protection on the sides of the track to avoid overwriting the information on the ongoing track, which was extremely inaccurate even though it was upgraded on both sides. and much more.
Therefore, and with the third factor at stake, the manufacturers did not know precisely whether to label their discs with PMR or CMR, because the quality eventually became both. Some ended up phoning her first and others second, until SMR came along.
SMR I can rewrite nearby tracks for later rewriting, a complex process that slows down the HDDs, but that increases their sensitivity and consequently their power.
Finally and in a different way when SMR came, which was chosen as an unwritten statement that PMR was the first technology in which CMR and SMR originated, although some manufacturers because they overcame and bet on CMR and their progress did not see it as such, Western Digital.