Memory and storage have always been a problem for computers and computer users. First, there’s the problem of having enough of them. Then, there’s the problem of having them be fast enough. For quite a few years now, the hard drive on a computer has been one of the slowest components.
Hard drives are essentially slow because they are electro-mechanical components. The electronics can be made to work fast, but the mechanics are limited. Ever since the first hard drives were produced in the 1950s, they’ve depended upon rotating metal disks and a seeker arm with a head attached to the end of it. Hard drives used in personal computers run at either 5400 RPM or 7200 RPM, with a few, high dollar units that run at 10,000 RPM. This rotational speed limits the speed that the data can be read from or written to the hard drive.
It has long been known that a true solid state hard drive would operate much faster than an electro-mechanical one could. The problem hasn’t been the concept; but rather coming up with an affordable solid state memory which could be used as a hard drive.
A Bit of History
In the 1970s, PROMs (programmable, read only memories) were used to provide limited permanent memory for small, computer controlled devices. The amount of memory available on one chip would be considered laughable today, but at the time, it was the best there was. PROMs, like all memory chips, consisted of rows and columns of gates, each of which could hold one bit of information. If it had voltage, it was a “1” if it didn’t, it was a “0.”
These PROMs were factory programmed units, which could only be programmed once; permanently. They were used to hold an operating program for the device they were installed in. These chips were usually socket mounted, rather than soldered to the board, so that the chip could be removed and replaced. Changing the information stored on the PROM required removing it and replacing it with a new PROM, not very efficient.
For engineering design purposes, an erasable version of the PROM was developed, called the EPROM (erasable programmable read only memory). To erase the EPROM required exposing it to ultraviolet light for 15 minutes. Once again, not very efficient, but workable; however, that was only workable in a laboratory situation, not for the general public to use day-to-day.
The next development was an electrically erasable version of the PROM, called the EEPROM (electrically erasable programmable read only memory). This was getting more like it; permanent memory which could be erased electrically. There was only one catch; it required 25 volts to erase the memory. In a device that was operating at 5 volts, that wasn’t very practical. Once again, this memory device was limited to the engineering laboratory and not available for consumer use.
Through time, EEPROMs have been improved upon, including the amount of voltage that’s required for them to be erased. These improved memory chips were even given a new name, Flash Memory. Our modern “flash drive” (or thumb drives) and “SSD” are both essentially flash memory.
Flash memory isn’t perfect. Like many other types of media, it can only be recorded and erased for so many cycles before it goes bad. This varies with the type of flash memory and its quality. There are a number of factors that affect this, such as the density of the circuitry and the controller circuitry. Flash memory manufacturers make their devices so that the memory will be used evenly, allowing it to “wear” evenly as well; rather than having just the first memory spots always being used.
SSD Versus HDD
Okay, so let’s compare SSD to HDD and see how they stack up. Each has its own advantages, so it’s hard to say which one is better.
Speed – SSD clearly beats out HDD for all speed specifications. There is virtually no seek time, along with the possibility of a much faster transfer rate.
Capacity – Large SSDs are still extremely rare. Although it is possible to buy them with as much as a 1 TB capacity, most are under 256 GB. Even then, a 128 GB SSD will cost more than double what a 1 TB HDD does.
Cost – HDD is the winner here, as SDD is still considerably more expensive than HDD. It will probably be years until SDD is truly cost effective.
Physical Size – SDD is much more compact than HDD. HDDs are made in two physical sizes: 3-1/2” and 2”. The larger being used for desktop computers and the smaller for laptops. All SDDs are made in the smaller size, making them more compact. They also don't have as much height as an HDD.
Fragmentation – As large files are written to a hard drive, they tend to have pieces scattered all over the place. This is called fragmentation. It slows down the hard drive, because the seek head needs to look for pieces of the file in different places. Although SDD drives also have fragmented files, it doesn’t matter, as there is virtually no seek time.
Durability –SDD can’t become physically damaged like HDD can, as there is no moving head to “crash” into the disk.
Longevity – Both have factors which limit the number of times that any particular portion of memory can be written and read.
Noise – Noise really isn’t much of an issue with modern hard drives. Even so, HDDs do make some noise, whereas SDDs don’t make any.
Choosing a SDD or HDD depends a lot on how important these factors are to you.
SDD Versus Thumb Drives
Since both SDDs and Flash drives, often referred to as Thumb drives are both Flash technology, one could easily question why not use a relatively inexpensive Thumb drive for their permanent memory storage, rather than the more expensive SDD. Good question.
While both devices are permanent memory and are based upon Flash technology, they are not in fact the same thing. There are three major differences which must be considered. First of all, the quality of the memory itself; SDDs can withstand more write/read cycles than Thumb drives can. Secondly, the controllers used for SDDs are far superior to those used in Thumb drives. This helps extend their longevity and the security of your data. Thirdly, there is the difference of interface.
Thumb drives are designed to be used with a USB port. While the newer USB 2.0 is considerably faster than the original USB 1.0, it is still not as fast as a SCSI port. Therefore, using a Thumb drive will slow down data transfer somewhat.