Finding compatible memory and a new hard drive for an older
Dan there is a memory manufacture that will tell how much your motherboard/Main board will handle and the fastest speed it can handle. it will even give you the exact specs on the memory. The memory company is "Crucial" (http://www.crucial.com/), use their memory "Crucial Memory Advisor tool" or let them search your computer with their "Crucial System Scanner tool". if your system is up and running and still attached to the internet. What I would do is let Crucial tell me what memory I needed. Do a screen print out of what type and speed of memory needed (if you plan to buy locally). If your system is too old and the stores no longer carry your memory. The next best thing is to go to "COMPUTER SWAP MEETS". Sometimes somebody at these "COMPUTER SWAP MEETS" has the memory you will need. memory will work with only slowest memory on your. As an example if memory is 70ns and you have a memory chip that is 60ns, then all of your memory will only operate at 60ns max. So if you are getting memory get it all with the same speed.
Well you can still look at faster RPM's, but will your computer utilize it? Does no good if your computer's drive will only support 20ms seek time.
IDE is more of an interface then it is a type of drive.
(1) (Integrated Development Environment) A set of programs run from a single user interface. For example, programming languages often include a text editor, compiler and debugger, which are all activated and function from a common menu.
(2) (Integrated Drive Electronics) A hardware interface widely used to connect hard disks, optical discs and tape drives to a PC. Introduced in 1986 with 20MB of storage, capacities increased a thousandfold in less than two decades. Compared to the SCSI interface, IDE has been the more economical choice.
The IDE interface is officially the AT Attachment (ATA) specification, and "IDE drives" and "ATA drives" are synonymous. The name came from the IBM PC/AT, which was the first PC to use the drives.
The controller electronics are built into the IDE drive itself, requiring a simple circuit in the PC for connection. IDE drives were attached to earlier PCs using an IDE host adapter card. Subsequently, two Enhanced IDE (EIDE) sockets were built onto the motherboard, with each socket connecting two drives via a 40-pin ribbon cable for CD-Rom's and similar devices and an 80-wire cable for fast hard disks (see below).
Master and Slave
IDE drives are configured as master and slave. Jumper pins on the drive itself are used to set up the first drive on the cable as master and the second one, if present, as a slave.
The ATAPI (ATA Packet Interface) was developed to allow CD-ROM drives to run over the IDE/ATA interface by using commands similar to SCSI drives. ATAPI is essentially ATA for peripherals such as CD-ROMs, DVDs and tapes.
The ATA Numbers
As improvements were made to the IDE/ATA interface, a new version number was added. ATA-2 (Fast ATA) defined the faster transfer rates used in Enhanced IDE (EIDE). ATA-3 added interface improvements, including the ability to report potential problems (see S.M.A.R.T.). Starting with ATA-4, either the word "Ultra" or the transfer rate was added to the name in various combinations. For example, at 33 MBytes/sec, terms such as Ultra ATA and ATA-33 have been used. In addition, Ultra ATA-33, DMA-33 and Ultra DMA-33 are also found. Following are the transfer rates for the various ATA modes.
(Serial ATA) A serial version of the ATA (IDE) interface, which has been the de facto standard hard disk interface for desktop PCs for more than two decades. The original Parallel ATA (PATA) interface was launched in 1986. SATA was introduced in 2002 at significantly higher speed, transferring data in each direction at 1.5 Gbps. A year later, SATA II increased speed to 3 Gbps.
SATA provides a point-to-point channel between motherboard and drive rather than the master-slave architecture in the parallel technology (see IDE).
Smaller Cables and Connectors
SATA uses a four-wire shielded cable up to one meter in length compared to the wide, flat, 18" PATA cables. SATA cables and connectors are considerably smaller than their PATA counterpart and take up a lot less space in the case.
SATA defines only internal drives, but eSATA (External SATA) enables them to reside in their own housing outside the computer and be plugged in as required. Providing an external, hot swappable drive solution similar to USB, SATA offers much higher speeds than the USB bus.
Cables up to two meters long attach eSATA drives to the computer either via an eSATA PCI card or directly to the internal SATA socket on the motherboard. A short cable extends the motherboard socket to the back of the computer. Designed for thousands of insertions, eSATA plugs and sockets are more rugged than internal SATA connectors. See IDE and SAS.
(Parallel ATA) Refers to the original ATA (IDE) technology that uses a parallel data channel from the controller to the disk drives. After Serial ATA drives became popular, the PATA term was coined to specifically refer to the parallel drives.
From Wikipedia, the free encyclopedia
Two SCSI connectors.Small Computer System Interface, or SCSI (pronounced skuh-zee), is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it can connect a wide range of other devices, including scanners and CD drives. The SCSI standard defines command sets for specific peripheral device types; the presence of "unknown" as one of these types means that in theory it can be used as an interface to almost any device, but the standard is highly pragmatic and addressed toward commercial requirements.
SCSI is an intelligent interface: it hides the complexity of physical format. Every device attaches to the SCSI bus in a similar manner.
SCSI is a peripheral interface: up to 8 or 16 devices can be attached to a single bus. There can be any number of hosts and peripheral devices but there should be at least one host.
SCSI is a buffered interface: it uses hand shake signals between devices, SCSI-1, SCSI-2 have the option of parity error checking. Starting with SCSI-U160 (part of SCSI-3) all commands and data is error checked by a CRC32 checksum.
SCSI is a peer to peer interface: the SCSI protocol defines communication from host to host, host to a peripheral device, peripheral device to a peripheral device. However most peripheral devices are exclusively SCSI targets, incapable of acting as SCSI initiatorsunable to initiate SCSI transactions themselves. Therefore peripheral-to-peripheral communications are uncommon, but possible in most SCSI applications. The Symbios Logic 53C810 chip is an example of a PCI host interface that can act as a SCSI target.
(Redundant Array of Independent Disks) A disk subsystem that is used to increase performance or provide fault tolerance or both. RAID uses two or more ordinary hard disks and a RAID disk controller. In the past, RAID has also been implemented via software only.
In the late 1980s, the term stood for "redundant array of inexpensive disks," being compared to large, expensive disks at the time. As hard disks became cheaper, the RAID Advisory Board changed "inexpensive" to "independent."
Small and Large
RAID subsystems come in all sizes from desktop units to floor-standing models (see NAS and SAN). Stand-alone units may include large amounts of cache as well as redundant power supplies. Initially used with servers, desktop PCs are increasingly being retrofitted by adding a RAID controller and extra IDE or SCSI disks. Newer motherboards often have RAID controllers.
RAID improves performance by disk striping, which interleaves bytes or groups of bytes across multiple drives, so more than one disk is reading and writing simultaneously.
Mirroring and Parity
Fault tolerance is achieved by mirroring or parity. Mirroring is 100% duplication of the data on two drives (RAID 1). Parity is used to calculate the data in two drives and store the results on a third (RAID 3 or 5). After a failed drive is replaced, the RAID controller automatically rebuilds the lost data from the other two. RAID systems may have a spare drive (hot spare) ready and waiting to be the replacement for a drive that fails.
The parity calculation is performed in the following manner: a bit from drive 1 is XOR'd with a bit from drive 2, and the result bit is stored on drive 3 (see OR for an explanation of XOR).
RAID 0 - Speed (Widely Used)
RAID level 0 is disk striping only, which interleaves data across multiple disks for performance. Widely used for gaming, RAID 0 has no safeguards against failure.
RAID 1 - Fault Tolerance (Widely Used)
Uses disk mirroring, which provides 100% duplication of data. Offers highest reliability, but doubles storage cost. RAID 1 is widely used in business applications.
RAID 2 - Speed
Instead of single bytes or groups of bytes (blocks), bits are interleaved (striped) across many disks. The Connection Machine used this technique, but this is rarely used because 39 disks are required.
RAID 3 - Speed and Fault Tolerance
Data are striped across three or more drives. Used to achieve the highest data transfer, because all drives operate in parallel. Using byte level striping, parity bits are stored on separate, dedicated drives.
RAID 4 - Speed and Fault Tolerance
Similar to RAID 3, but uses block level striping. Not often used.
RAID 5 - Speed and Fault Tolerance (Widely Used)
Data are striped across three or more drives for performance, and parity bits are used for fault tolerance. The parity bits from two drives are stored on a third drive and are interspersed with user data. RAID 5 is widely used in servers.
RAID 6 - Speed and Fault Tolerance
Highest reliability because it can recover from a failure of two disks, but not widely used. Similar to RAID 5, but performs two different parity computations or the same computation on overlapping subsets of the data.
RAID 10, RAID 100 - Speed and Fault Tolerance
RAID 10 is RAID 1 + 0. The drives are striped for performance (RAID 0), and all striped drives are duplicated (RAID 1) for fault tolerance.
RAID 100 is RAID 10 + 0. It adds a layer of striping on top of two or more RAID 10 configurations for even more speed.
To tell you which one is faster, that would be determined by your needs. Which one is fastest, still it is the one with the fastest seek time. There you have it time for you to make a decision. What else would determine what types of drives, your motherboard/Main board. Does it have connections for RAID, SATA OR PATA? It just so happens that my motherboard/Main board has all three. But not a lot of Motherboards/Main boards have all three options.
Well Dan that is about it for now. Hope this helps.