In 1993 Western Digital brought EIDE (Enhanced IDE) onto the market. EIDE is a standard designed to overcome the constraints of ATA while at the same time maintaining backward compatibility. EIDE supports faster data transfer rates – with Fast ATA capable of burst rates up to a 16.6 MBps – and higher disk capacities, up to 137GB since mid-1998, when the previous 8.4GB limit was raised.
The four possible devices on an EIDE system are handled by two channels. Each channel supports two devices in a master/slave configuration. The primary port is generally connected to a local bus (for example, PCI), and this is set to the same address and IRQ setting as it was on the standard IDE system. This ensures backward compatibility with IDE systems and prevents conflicts which would otherwise crop up with operating system software, or other software which communicates with an IDE device. The old IDE system must be set up to cope with the enhancements in EIDE (higher performance and increased hard disk capacity) and this is enabled by additional software.
When the host needs data to be either read or written, the operating system first determines where the data is located on the hard drive – the head number, cylinder, and sector identification. The operating system then passes the command and address information to the disk controller, which positions the read/write heads over the right track. As the disk rotates, the appropriate head reads the address of each sector on the track. When the desired sector appears under the read/write head, the necessary data is read into the cache buffer, usually in 4K blocks. Finally, the hard drive interface chip sends the data to the host.
The ability to support non-disk peripherals such as CD-ROM drives and tape drives was made possible by the ATAPI (AT Attachment Packet Interface) specification, defined by Western Digital. The ATAPI extension of the ATA protocol defines a single command set and single register set allowing other devices to share the ATA bus with traditional ATA HDDs. It includes several commands which are specific to CD-ROM devices, including the Read CD command group as well as a CD speed-select command.
In addition to ATAPI, EIDE supports transfer standards developed by the ATA Committee. The Programmed Input/Output (PIO) modes are a range of protocols for a drive and IDE controller to exchange data at different rates which define specifications for the CPU’s involvement in data transfer between the hard drive and memory. Many drives also support Direct Memory Access (DMA) operation as an alternative protocol to PIO modes. This is where the drive takes over the bus (bus mastering) and transfers data directly to system memory. This is better for multitasking PCs as the CPU can do other things while data transfer occurs, although its only in systems using Triton HX/VX or later chipsets that the CPU can use the memory or ISA buses while the PCI bus is in use. An OS device driver is needed for DMA, and a system’s BIOS must also support these specifications to take advantage of them.
The hard drive industry subsequently adopted a number of approaches to enhance performance further. The first was to enlarge drive capacity. This was accomplished by making the tracks on the disk closer together (track density) and the data written on each track more dense (linear density). By making more data available during each rotation internal data transfer rates were effectively increased. There then followed number of vendor-specific measures to improve data transfer rates further, such as producing higher rpm drives, or modifying the cache buffer algorithms. The ultimate step was to modify the ATA/IDE protocol itself.
The original ATA specification was for connecting drives to the ISA bus and host transfers were limited to 2-3 MBps. The newer ATA-2 or Fast ATA interface connect to a local bus instead and the higher bandwidths available on local bus architectures meant massively improved data throughput. Since systems and drive vendors are allowed to label their products as EIDE even when supporting only a subset of its specifications, several vendors use the term Fast ATA (AT Attachment) for their EIDE hard drives that support PIO Mode 3 and Multiword Mode 1 DMA, and Fast ATA-2 for drives that support PIO Mode 4 and Multiword Mode 2 DMA.
- What Is The System Bus?
- ISA Bus – Industry Standard Architecture
- Local Bus Interfaces
- PCI Bus Interfaces
- What is AGP and AGP Pro?
- Internal Interfaces Summary
- PCI-X Interfaces
- PCI Express Interfaces
- IDE Interfaces
- EIDE Interfaces
- Hard Disks – What IS ATA and Ultra ATA?
- Serial ATA (SATA) interface guide
- SCSI Explained – With Pictures
- SCSI Interface Evolution
- Fibre Channel Interfaces
- Hard Disks – What is Serial Storage Architecture?
- I/O Interface Standards
- How It Works: The Idea and Technology Behind USB
- IEEE 1394 Interfaces
- USB 2.0 Intefaces
- FireWire 800 Interfaces
Mwaka 1993, Western Digital ilianzisha EIDE (Enhanced IDE). EIDI ni kiwango iliyoundwa kushinda vikwazo vya ATA wakati wakati huo huo kudumisha backward compatibility. EIDI inasaidia kasi ya uhamisho wa data - na ATA ya haraka inayoweza kufikia kasi ya burst hadi 16.6 MBps - na uwezo wa diski ya juu, hadi 137GB tangu katikati ya 1998, wakati kikomo cha awali cha 8.4GB kiliongezwa. Vifaa vinne vinavyowezekana kwenye mfumo wa EIDE vinashughulikiwa na njia mbili. Kila kituo inasaidia vifaa viwili katika bwana / mtumwa Configuration. Kwa kawaida, bandari ya msingi imeunganishwa na basi la ndani (kwa mfano, PCI), na hii imewekwa kwa anwani sawa na kuweka IRQ kama ilivyokuwa kwenye mfumo wa kawaida wa IDE. Hii inahakikisha backward compatibility na mifumo ya IDE na kuzuia migogoro ambayo ingekuwa vinginevyo crop up na programu ya mfumo wa uendeshaji, au programu nyingine ambayo anawasiliana na kifaa IDE. Mfumo wa zamani wa IDE lazima uandaliwe ili kukabiliana na maboresho katika EIDE (utendaji wa juu na uwezo wa diski ngumu iliyoongezeka) na hii inawezeshwa na programu ya ziada. Wakati mwenyeji anahitaji data kuwa ama kusoma au kuandika, mfumo wa uendeshaji kwanza huamua ambapo data iko juu ya diski ngumu <unk> nambari ya kichwa, silinda, na kitambulisho cha sekta. Mfumo wa uendeshaji kisha hupitisha amri na anwani ya habari kwa diski controller, ambayo nafasi kusoma / kuandika vichwa juu ya kufuatilia haki. Diski inapozunguka, kichwa kinachofaa husoma anwani ya kila sehemu ya reli. Wakati sekta inayotakiwa inaonekana chini ya kichwa kusoma-kuandika, data muhimu ni kusoma katika buffer cache, kwa kawaida katika 4K vitalu. Hatimaye, hard drive interface chip hutuma data kwa mwenyeji. Uwezo wa kusaidia vifaa visivyo vya diski kama vile CD-ROM na diski za mkanda ulifanywa iwezekanavyo na ATAPI (AT Attachment Packet Interface) maalum, iliyofafanuliwa na Western Digital. ATA ni kifungu cha ATA ambacho kinajumuisha seti moja ya amri na seti moja ya usajili, na inaruhusu vifaa vingine kushiriki bus ya ATA na ATA ya jadi. Ni pamoja na amri kadhaa ambayo ni maalum kwa vifaa CD-ROM, ikiwa ni pamoja na kusoma CD kundi amri kama vile CD kasi-chagua amri. Pamoja na ATAPI, EIDE inasaidia viwango vya uhamisho vilivyotengenezwa na Kamati ya ATA. Programu ya Input-Output (PIO) ni aina ya itifaki kwa ajili ya gari na IDE controller kubadilishana data kwa viwango tofauti ambayo kufafanua vipimo kwa ajili ya CPU ya ushiriki katika uhamisho wa data kati ya diski ngumu na kumbukumbu. Wengi madereva pia kusaidia Direct Memory Access (DMA) operesheni kama itifaki mbadala kwa PIO modes. Hii ni ambapo gari inachukua juu ya basi (basi mastering) na uhamisho wa data moja kwa moja kwa kumbukumbu ya mfumo. Hii ni bora kwa ajili ya PCs multitasking kama CPU inaweza kufanya mambo mengine wakati uhamisho wa data hutokea, ingawa ni tu katika mifumo ya kutumia Triton HX au baadaye chipsets kwamba CPU inaweza kutumia kumbukumbu au ISA mabasi wakati PCI bus ni katika matumizi. DMA inahitaji kifaa cha OS cha kuendesha gari, na BIOS ya mfumo lazima pia iunge mkono vipimo hivi ili kuitumia. Sekta ya diski ngumu baadaye ilipitisha mbinu kadhaa za kuboresha utendaji zaidi. Jambo la kwanza lilikuwa kuongeza uwezo wa kuendesha gari. Hii ilifanywa kwa kufanya nyimbo kwenye diski karibu pamoja (wingi wa nyimbo) na data iliyoandikwa kwenye kila wimbo zaidi dense (wingi linear). Kwa kufanya data zaidi inapatikana wakati wa kila mzunguko viwango vya uhamisho wa data ya ndani walikuwa ufanisi kuongezeka. Kisha ilifuata idadi ya hatua maalum za muuzaji ili kuboresha viwango vya uhamisho wa data zaidi, kama vile kuzalisha madereva ya juu ya rpm, au kurekebisha algorithms ya buffer ya cache. Hatua ya mwisho ilikuwa kurekebisha ATA / IDE itifaki yenyewe. ATA awali maalum ilikuwa kwa ajili ya kuunganisha drives kwa ISA bus na uhamisho mwenyeji walikuwa mdogo kwa 2-3 MBps. ATA-2 au Fast ATA interface ni njia ya kuunganisha na bus ya ndani, na bandwidth ya juu inapatikana kwenye usanifu wa basi ya ndani. "Kwa kuwa vifaa vya EIDV vinaweza kuonekana kama ""EIDV"" wakati wa kuunganisha, wengi wa wauzaji wa EIDV hutumia neno ""Fast ATA"" kwa ajili ya diski ngumu za EIDV zinazounga mkono PIO Mode 3 na Multi-Word Mode 2 na PIO Mode 4." - Basi la Mfumo ni nini? - ISA Bus <unk> Viwanda Standard Architecture - Interfaces Local Bus - PCI Bus Interfaces - Nini AGP na AGP Pro? - Interfaces ya ndani muhtasari - PCI-X Interfaces - PCI Express Interfaces - IDE Interfaces - EIDE Interfaces - Disks Hard  Nini ATA na Ultra ATA? - Serial ATA (SATA) interface mwongozo - SCSI Alieleza <unk> Pamoja na Picha <unk> SCSI Interface Evolution <unk> Fibre Channel Interfaces <unk> Disks Hard <unk> Nini Serial Storage Architecture? IATA Interface Standards: Jinsi Inavyofanya Kazi: Wazo na Teknolojia Nyuma ya USB - IEEE 1394 Interfaces - Interfaces za USB 2.0 - Interfaces za FireWire 800