Home Technology Hard Disk Controller

Hard Disk Controller

Controller type

Usually two types of controllers are used: IDE and SCSI. IDE is the abbreviation of IntegratedDriveElectronics (Integrated Drive Electronics), and SCSI is SmallComputerSystemsInterface (Small Computer System Interface) Abbreviation.


1 Working principle

2 IDE controller

3 SCSI controller

4 SAS technology

5 Common mistakes

6 Related entries

7 Reference materials

How it works


The hard disk controller is the disk drive adapter. It is the interface device between the computer and the disk drive. It receives and interprets commands from the computer, and sends various control signals to the disk drive. Check the status of the disk drive and write data to and read data from the disk in accordance with the specified disk data format. There are many types of disk controllers, but its basic composition and working principle are basically the same. It is mainly composed of a control logic circuit connected to the computer system bus, a microprocessor, and completes the read and write data separation and write data compensation. Data decoding and encoding circuit, data error detection and error correction circuit, logic circuit that controls data transmission, serial-to-parallel conversion and formatting according to commands sent by the computer, read-only memory for storing basic input and output programs of the disk, and The data exchange buffer and other parts.

Hard Disk Controller-IDE Controller

Serial Port

IDE controllers are often made in the motherboard and can support up to 4 Hard disks can transfer data up to 66 Megabytes (MB) per second, but many IDE controllers can only reach 33 Megabytes. There are several variants of IDE controllers, the most common is ATA: AdvancedTechnologyAttachment (additional advanced technology), ATA is the second controller invented by IBM installed in the hard disk, which can greatly accelerate the speed of data transmission. At present, ATA-3 and ATA-4, which have further improved performance, are being widely used by audio workstations. If you don't know which kind of controller is used in your computer, you can refer to the manual of the motherboard and hard drive.

ATA can be divided into the following categories:


The original hard disk controller is the same concept as IDE.


Usually regarded as fast ATA (FASTATA) or enhanced IDE (EIDE). EIDE was first introduced by WesternDigital, with a new BIOS that allows management of hard drives with a capacity of 504MB. Quantum and Seagate launched FastATA at the same time, which can transmit data faster, supports a capacity greater than 504MB, and can connect 4 devices, including CD-ROM and tape drives.

ATA-3ATA-3 followed ATA-2, but the performance has not improved much. Usually ATA-3 is equivalent to EIDE or FastATA.


ATA-4 is also called UltraATA or UltraDMA, including ATAPI4 regulations. ATAPI is the abbreviation of "ATAttachmentwithPacketInterface", which allows CD-ROM and tape drives to share the ATA bus with ATA hard disks. ATA-4 is the most commonly used controller for computers today.

Hard Disk Controller


ATA-5 is a regulation under development and can support speeds exceeding 66MB Transmission, while improving reliability by improving internal algorithms. A new UDMA80 cable is required, and the new motherboard will support ATA-5.


Many Macintosh computers including G3 and G4 also implement IDE, EIDE or UDMA regulations. Any standard PC hard disk can be used, but it needs to be formatted separately.

Data throughput

Because of the introduction of multiple ATA specifications, the relevant specifications of throughput are derived:


The maximum data throughput is 66MB per second.

ATA/100 is similar to ATA/66, but the maximum data throughput is 100MB per second. The motherboard and hard disk must support ATA/100 at the same time. Some third-party PCI cards can help the computer run ATA/100. Drive.

Hard Disk Controller-SCSI Controller

SCSI Controller

SCSI (pronounced as scuzzy) is a very advanced hard disk control But usually its price is higher than IDE, so it is difficult to popularize. SCSI can support multiple hard disks, CD-ROMs, scanners and other devices. It can connect up to 30 devices and peripherals in a daisy chain, which is most suitable for recording studios that require huge capacity. SCSI controllers are traditionally faster than IDEs, and can reach a speed of 160MB per second. New controllers under development can even reach 320MB per second. Just like IDE, SCSI also has some different versions. If your DAW needs the best performance, use the standard of 24bit/96Khz or 24bit/192KHz and store a large amount of data, you should consider SCSI first.

The use of SCSI in the system requires two aspects of equipment: SCSI controller, usually represented as a PCI card, and SCSI devices such as hard disks, CD-ROMs, etc., they need to be connected with SCSI cables. The final choice depends on your budget and the nature of your work. If you want your DAW to have the most audio tracks, you should use a 15,000RPM (revolutions per minute) SCSI160 hard drive.

SCSI regulations


SCSI1 is the original regulation in 1986, the first SCSI standard. A maximum of 7 devices can be connected, and the maximum transmission speed is 5MB per second, which was of epoch-making significance at the time.


SCSI2, also known as FastSCSI (Fast SCSI), has made many improvements on the basis of SCSI1, but it was not widely used until 1994. SCSI-2 streamlined some inexplicable options, increased reliability, and increased the transmission speed to 10MB per second.

FastWideSCSI FastWideSCSI is a type of SCSI2. The bus width is doubled to become a 16bit bus. The transmission speed is increased to 20MB per second. A controller can connect 14 devices.

UltraSCSI UltraSCSI is also a type of SCSI2, using the original 8-bit bus, but the maximum transmission speed is 20MB per second, and the number of devices that can be connected to a single controller is still 7.

UltraWideSCSI UltraWideSCSI is called WideUltraSCSI. It uses a 16bit bus like FastWideSCSI. The maximum transmission speed is 40MB per second. A controller can connect 14 devices.


Ultra2SCSIUltra2SCSI uses an 8bit bus, but the internal clock speed is doubled, and the maximum transmission speed reaches 40MB per second. There are still 7 devices that can be connected to a single controller.


WideUltra2SCSI is the fastest SCSI in a period of time, using 16bit bus, the maximum transmission speed is 80MB per second, the internal clock speed is doubled, a controller can connect 7 pieces Equipment.

Ultra3SCSI Ultra3SCSI, also known as SCSI160, is a very fast SCSI standard. The maximum transmission speed of the controller using the 32bitPCI slot is 80MB per second, and the maximum transmission speed of the controller using the 64bitPCI slot is 160MB per second, and one controller can connect to 14 devices.

SCSI3 has gradually lowered the price, and it will be the best choice for 24bit/96KHz recording hard drives.


Ultra320SCSI is a new SCSI standard that has just begun to be applied. UltraSCSI320 uses a 32bitPCI slot to allow a maximum transmission speed of 160MB per second, and a controller using a 64bitPCI slot allows a maximum transmission speed of 320MB per second. SCSI320 uses 16bit bus and is compatible with SCSI160.

Hard Disk Controller-SAS Technology

Embedded SATA Hard Disk Controller

SAS (SerialAttachedSCSI) is serial SCSI technology, It is a new type of disk connection technology. It combines the advantages of existing parallel SCSI and serial connection technologies (Fibre Channel, SSA, IEEE1394, InfiniBand, etc.), uses serial communication as the protocol infrastructure, adopts SCSI-3 extended instruction set and is compatible with SATA devices, and is multi-level The storage device is connected to the protocol stack. SAS disks are disks that use this interface technology. According to industry predictions, SAS disks will soon replace SCSI disks and become the mainstream disk type.

Characteristics of SAS:

1. Better performance:

Point-to-point technology reduces address conflicts and the slowdown of daisy chain links;


A dedicated signal path is provided for each device to ensure the maximum bandwidth;

Data operation in full duplex mode ensures the most effective data throughput;

2. Simple cable connection:

Slimer cable with smaller connector;

3. Better scalability:

Yes Connect more disk devices at the same time.

Since Serial SCSI (SAS) is a point-to-point structure, in addition to improving performance, each device is connected to a designated data path to increase bandwidth. The SAS cable structure saves space, thereby improving the heat dissipation and ventilation capabilities of SAS hard disk servers. Under normal circumstances, larger parallel cables will cause electronic interference, and the SAS cable structure can solve this problem. In addition, the SAS structure has very good expansion capabilities, which can connect up to 16384 disk devices.

Serial SCSI (SAS) hard disks use the same interface as S-ATA, but use more signals, so SAS hard disks cannot be connected to S-ATA hard disk controllers. SAS is a universal interface, supporting SAS and S-ATA, and SAS controllers can support SAS and SATA disks. S-ATA uses the signal subset of the SAS controller, so the SAS controller supports S-ATA hard drives.

Transition interface

The initial SAS hard disk uses a 2.5-inch package, so that the rack server can support more hard disks. Some manufacturers have introduced standard 3.5-inch SAS hard disks; initial products The speed is 10000RPM, and 15000RPM products have also come out. SAS hard drives have the same or better performance than SCSI hard drives with the same rotational speed. The serial interface reduces the size of the cable and allows faster transmission speeds. SAS hard drives can transmit data up to 3.0Gbit/sec.

Each SAS cable has 4 cables, 2 input and 2 output. SAS can read and write data at the same time, and full-duplex data operations improve data throughput efficiency.

As a new storage interface technology, SAS is not only functionally comparable to FibreChannel, but also compatible with SATA, so it is recognized by the industry as the best choice to replace parallel SCSI. The advantages of SAS are mainly reflected in: flexibility, compatibility with SATA, saving investment for users; scalability, a SAS domain can directly connect up to 16384 devices; excellent performance, point-to-point architecture improves performance as the number of ports increases; more reasonable The cable design provides more effective heat dissipation in a high-density environment. There are usually 4 basic indicators to measure the pros and cons of a technology, namely performance, reliability, scalability and cost. Looking back at the development history of serial disk technology, from Fibre Channel, to SATA, to SAS, several technologies have their own strengths. The earliest serialized storage technology that appeared in Fibre Channel can meet the storage needs of high performance, high reliability and high scalability, but the price remains high; the cost of SATA hard disks has dropped, but they are mainly used for near-line storage and non-linear storage. Critical applications, after all, are not satisfactory in terms of performance; SAS should be regarded as an all-rounder, which can support SAS and SATA disks, easily meet the storage needs of different cost performance, and is a high-performance, high-reliability and high-scalability solution.

Hard Disk Controller-Common Errors

Parallel Port

The most common fault of hard disk is boot-type fault, that is, hard disk can not start, etc. . When a boot-type failure occurs, the system will have many error prompts. If we understand these prompts, it will be very helpful for solving hard disk problems:

1. Error prompt: HDDcontrollerfailure

Error explanation: The hard drive control failed.

The reason for the error: This is a timeout error caused by the drive not completing the operation within the specified time after the POST program (automatic detection program in BIOS) sends a seek command to the drive when starting the machine. If this error occurs, it is possible that your hard disk has been damaged.

2. Error prompt: HDCcontrollerfail

Error explanation: The hard disk controller control failed.

The reason for the error: this type of failure is a hardware failure. After the POST program sends a reset command to the controller, no interrupt response from the controller is received within the specified time. It may be that the controller is damaged or the cable is not connected properly. In addition, the controller control failure is also related to whether the hard disk parameter settings are correct.



Error explanation: The BASIC system is not solidified and the system stops.

This kind of error often appears on 486 and earlier machines, and it is a reminder that only appears on very old machines. The role of the master boot program when the system starts is to find an active partition (a bootable partition) of the hard disk among the four entries in the partition table. None of the hard disks are active partitions, and the system does not know where to boot the operating system. It can only execute an interrupt, calling the BASIC program that was cured in the BIOS in the early computer. If the BASIC is not cured, this error will occur and cause a crash. So the easiest way to fix it is to use FDISK to set up an active partition on the hard disk. If your computer no longer solidifies the BASIC program, this error will no longer occur.

This article is from the network, does not represent the position of this station. Please indicate the origin of reprint