On the surface, the Seagate Momentus hard disk looks similar to just about every other mobile drive on the market. It meets the same 2.5" laptop and notebook size specifications, so replacing a notebook drive with this unit is a straight forward swap - this is, however, is where things start to change.
Seagate has put a lot of work into the third generation of Momentus hard disk drives in the 5,400 RPM range. For starters, they are the largest capacity of any notebook drive currently on the market, offering a whooping 160GB of storage space. This is achieved by using another technology, called Perpendicular Magnetic Recording or PMR.
Next is an increase in cache size from 4MB (5400.2) to an 8MB cache buffer on the 5400.3 range. This allows for a doubling of size of the storage buffer and reduces lag when it comes to accessing the hard disk. The last feature on the list is a choice of either 44-pin Parallel ATA interface (the standard Notebook IDE Interface we are used to) or a Serial ATA interface for the next generation of laptops already equipped with SATA internal interfaces.
(Editor Note: We were incorrect in saying the previous model only had 4MB cache, it in fact also had 8MB cache. Sorry for the error!)
Perpendicular Magnetic Recording changes the way that the data is stored on a hard disk platter. Normally the magnetic bits are lined up in a longitudinal array. This means that the data pits are larger then packed onto a drive, by rotating them 90 degree and storing them on a perpendicular access, the amount of bits that can be stored on a drive increased from 20% up to a massive 50%. This technology means that we can start to see drives for notebooks passing the 200GB mark and even hitting the terabyte mark by next year, according to some sources.
The bottom of the drive shows the circuitry. Most of the IC's are sandwiched between the controller board and the bottom of the HDD casing - this means little to no chance of having them short out accidentally.
Here we see the drive that was supplied to us uses the older 44-pin IDE interface common to most notebooks still in use today. While the SATA one would be a nicer choice, it's still good to see that the older generation is still getting some upgrades. There is no actual power connector on the unit; the extra 4 pins on the drive supply the 5v that powers the internal motors, heads and circuits.
Lastly we have this little baby. This isn't part of the drive package but it is what we used to connect the drive to our test bed. Rather than use a notebook, we wanted to use a full powered desktop to eliminate any bottlenecks. We wanted to get the full performance results from the HDD itself. To this end we connected the drive though this 44-pin to 40-pin converter on our Intel Pentium D test bed system.