Yes, here is what I found about that 4GB hard drive in the Nokia N91. There is ALOT more detail about that hardrive..if u want the entire N91 review or other Nokia reviews by this gentlemen, pm me
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The drive is manufactured by Hitachi, I shall remind you that it has purchased the division of IBM, which claimed the title of pioneers in the field of these devices. The name of the line-up was corresponding - Microdrive. Nokia N91 features a new model of this drive ? Microdrive 3K4-4. Its characteristics are quite good and to some extent can be compared to flash memory:
Cache buffer 128 Кб
Speed 3600 rpm
Latency Average ? 8.33 ms
Media Transfer Rate ? 57.1-97.9 (max. Mbits/s)
Sustained Data Rate ? 4.3-7.2 (Mb/s)
Seek time (read, typical) ? 12 ms, track to track ? 1 ms, full track ? 22 ms
Limit of 300000 cycles of on/off
Those, who are fond of digging in the internal part of phones, will be surprised by the fact that the hard drive, featured in Nokia N91 has the dimensions of 32х24 mm, rather than the standard 42х36 mm. The explanation lies in use of CompactFlash II connector by most of the companies, incorporating Microdrive disks into their solutions, though Nokia declined the idea of using a disk in the standard shell. It means that the hard drive, presented here is an analogue of Microdrive 3K4-4, but it differs in shell, which was replaced by a special socket on Nokia N91 chip (located lower than the camera?s module, but above the battery, exactly under the safety casing). The developers applied here not only floating support for the disk, but also a special casing, which amortizes all blows. From above the disk is also protected by a soft rubber cover, which deflects frontal blows and lowers noise level at the same time. To tell the truth, one can rarely hear the disk itself ? only in cases when you hold the handset in your hands do some inhumane experiments, e.g. open the rear lid and instantly pull out the battery. The interface connector is designed specially for this model and is aimed at lowering the place, occupied by the hard drive.
The cover has a pressure sensor, so once the battery's cover is removed, the disk automatically turns off. This process takes up to one second. Another precaution is acceleration sensor ? in case the device is falling from a height more than 1 meter, the hard disk switches off, so it may avoid a certain amount of damage, since exactly when turned on, the disk is vulnerable to mechanical effects. For good reason we didn?t try to carry out stress tests, since all throws could hurt the screen, rather than the hard drive, because protection level featured in Nokia N91 is higher than in all other devices using Microdrive. There are some numbers regarding durability of iPOD Mini ? after a certain period operation most of devices work fine, and no wonder about it, as here the developers also used the system, applied to N91.