Sun Microsystems Ultra 5, Service Manual

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Appendix C Functional Description C-7
C.1.2.7 EIDE Interface
The enhanced integrated drive electronics (EIDE) interface is a hard drive interface
that is also called an ATA bus interface. With the advent of faster hard drives, the
definition of the EIDE interface has been expanded to include new operating PIO
and DMA modes. The five PIO modes, numbered zero through four, offer
increasingly faster interface speeds, with the higher-numbered mode being the
faster. PIO modes 0, 1, and 2 correspond to the EIDE interface as originally defined.
PIO mode 3 defines a maximum transfer rate of 11.1 Mbytes per second and PIO
mode 4 defines a maximum transfer rate of 16.67 Mbytes per second. Additional
DMA modes have also been defined with Multiword DMA wired 0 corresponding to
the original DMA interface and DMA modes 1 and 2 being faster transfer rates.
Multiword DMA mode 2 is the same speed as the new PIO mode 4.
The following figure shows the EIDE interface functional block diagram.
FIGURE C-3
EIDE Interface Functional Block Diagram
Cable Electrical Requirements (With Optional Secondary Hard Drive)
In Ultra 5 systems with an optional secondary hard drive, automatic cable selection
of a master and a slave hard drive is allowed without the need to change drive
jumpers. An ATA cable is used to interface the host with the hard drives. Device 0
must be installed on the connector nearest on the cable to the host and device 1 must
be installed on the connector farthest from the host.
PCI
CH2_CS1, 3#
CH2_INTQ
CH2_DMARQ, DMACK
DIRQ#/DIOW#, DRST#
DA[2:0]
CH1_CS1,3#
CH1_INTRQ
CH1_DMARQ, DMACK
DD[15:0]
40-pin
40-pin
connector
connector
IDE
connector
(channel 2)
IDE
connector
(channel 1)
PCI-EIDE
interface