If you're upgrading a system that has a PIO mode device installed, if possible reconfigure it for DMA. Both devices will function, but the throughput of the DMA device will be crippled. That said, you should not use elderly PIO devices on the same interface as a DMA device. But you can connect any ATA or ATAPI drive to any ATA interface with assurance that it will function, albeit perhaps not optimally.
Newer drives cannot yield their highest performance when connected to an old ATA interface, just as a new interface can't improve the performance of an older drive. With minor exceptions, there are no outright compatibility conflicts between new ATA devices and old ATA interfaces or vice versa. Only very old hard drives and optical drives are limited to PIO mode anyway, so replacing them is a no-brainer.Ĭompatibility Between Old and New IDE Devices
#Hard disk drive connectors upgrade
When you upgrade a system, if you find any drives that support only PIO mode, replace them. That cripples throughput and puts a heavy load on the processor, bogging down the system whenever the drive is accessed.Īll modern ATA and ATAPI devices support DMA mode, but for backward compatibility, most can be set to use PIO mode. If either device on an ATA channel uses a PIO mode, both devices must do so. DMA mode transfers are much faster and occur without processor intervention. PIO mode transfers are much slower and require the processor to arbitrate transfers between the device and memory. That is, the drive that was master on the 40-wire cable becomes slave on the 80-wire cable, and vice versa.ĪTA defines two classes of transfer mode, called PIO Mode ( Programmed I/O Mode) and DMA Mode ( Direct Memory Access Mode). However, if the drives are jumpered as CSEL, replacing a 40-wire CSEL cable with an 80-wire cable causes the drives to exchange settings. If the drives are jumpered as master/slave, substituting an 80-wire cable works fine. Although all Ultra DMA cables support drives jumpered as either master/slave or CSEL, that does not mean you can freely substitute an 80-wire cable for a 40-wire cable. Note the difference between using a 40-wire CSEL cable and an 80-wire cable for CSEL operation. The best rule is simply never to use a 40-wire cable to connect a hard drive. But if you connect two CSEL drives to a standard cable, both function as master, which may result in anything from subtle problems to (more likely) the system being unable to access either drive. If you substitute a standard cable for a CSEL cable and connect one drive jumpered as CSEL to that cable, it will function properly as master. If you substitute a CSEL cable for a standard cable, drives that are jumpered as master or slave function properly. Keep unlabeled 40-wire CSEL cables segregated from standard cables. Because 40-wire ATA cables do not ground pin 34, the system can detect at boot whether a 40-wire or 80-wire cable is installed.
This is done by grounding pin 34 in the blue connector, which attaches to the interface. Color-coded connectors were not specified for earlier ATA cables.īecause an UltraDMA cable is required for UltraATA-66 or faster operation, the system must have a way to detect if such a cable is installed. All UDMA cables are CSEL cables, and may be used in either cable select mode or master/slave mode. A UDMA cable may be used with any ATA/ATAPI device and should be for more reliable functioning but is required for best performance with UltraATA-66, -100, and -133 devices (UDMA Modes 4, 5, and 6, respectively). The additional 40 wires are dedicated ground wires, each assigned to one of the standard 40 ATA pins. An UltraDMA ( UDMA) cable uses an 80-wire ribbon cable and 40-pin connectors in all three positions.