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In computer hardware, a host controller, host adapter, or host bus adapter (HBA) connects a host system (the computer) to other network and storage devices. The terms are primarily used to refer to devices for connecting SCSI, Fibre Channel and eSATA devices. However, devices for connecting to IDE, Ethernet, FireWire, USB and other systems may also be called host adapters. The term network interface controller (NIC) is more often used for devices connecting to computer networks, while the term converged network adapter can be applied when protocols such as iSCSI or Fibre Channel over Ethernet allow storage and network functionality over the same physical connection. These can include TCP offload engines. ==SCSI== (詳細はdevice driver, linked to the operating system, controls the host adapter itself. In a typical parallel SCSI subsystem, each device has assigned to it a unique numerical ID. As a rule, the host adapter appears as SCSI ID 7, which gives it the highest priority on the SCSI bus (priority descends as the SCSI ID descends; on a 16-bit or "wide" bus, ID 8 has the lowest priority, a feature that maintains compatibility with the priority scheme of the 8-bit or "narrow" bus). The host adapter usually assumes the role of SCSI initiator, in that it issues commands to other SCSI devices. A computer can contain more than one host adapter, which can greatly increase the number of SCSI devices available. Major SCSI adapter manufacturers are HP, ATTO Technology, Promise Technology, Adaptec, and LSI Corporation. LSI, Adaptec, and ATTO offer PCIe SCSI adapters which fit in Apple Mac, on Intel PCs, and low-profile motherboards which lack SCSI support due to the inclusion of SAS and/or SATA connectivity. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Host adapter」の詳細全文を読む スポンサード リンク
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