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Cheetah 4LP Product Manual, Rev. B
3.0
General description
Cheetah 4LP drives combine magnetoresistive (MR) heads, partial response/maximum likelihood (PRML) read
channel electronics, embedded servo technology, and a SCSI-3 (Fast-20) interface to provide high perfor-
mance, high capacity data storage for a variety of systems including engineering workstations, network serv-
ers, mainframes, and supercomputers.
Fast-20 (also known as Ultra SCSI) is a negotiated transfer rate. This transfer rate will occur only if your host
adapter also supports Fast-20 data transfer rates. This drive also operates at SCSI-1 and SCSI-2 data transfer
rates for backward compatibility with non-Fast-20 capable SCSI host adapters.
Table 1 lists the features that differentiate the various Cheetah 4LP SCSI-3 Fast-20 (Ultra SCSI) models.
Table 1.
Drive model number vs. differentiating features
Number
Model number
of heads
ST34501N
8
ST34501W
8
ST34501WD
8
ST34501WC
8
ST34501DC
8
The drive records and recovers data on 3.5-inch (86 mm) non-removeable discs.
The drive supports the Small Computer System Interface (SCSI) as described in the ANSI SCSI-2 interface
specifications to the extent described in this manual (volume 1), which defines the product performance char-
acteristics of the Cheetah 4LP family of drives, and the SCSI Interface Product Manual (volume 2), P/N
77738479, which describes the general interface characteristics of this and other families of Seagate SCSI
drives.
The drive's interface supports multiple initiators, disconnect/reconnect, self-configuring host software, and
automatic features that relieve the host from the necessity of knowing the physical characteristics of the targets
(logical block addressing is used).
The head and disc assembly (HDA) is sealed at the factory. Air circulates within the HDA through a non-
replaceable filter to maintain a contamination-free HDA environment.
Refer to Figure 2 for an exploded view of the drive. This exploded view is for information only—never disas-
semble the HDA and do not attempt to service items in the sealed enclosure (heads, media, actuator, etc.) as
this requires special facilities. The drive contains no replaceable parts. Opening the HDA voids your warranty.
Cheetah 4LP drives use a dedicated landing zone at the innermost radius of the media to eliminate the possi-
bility of destroying or degrading data by landing in the data zone. The drive automatically goes to the landing
zone when power is removed.
An automatic shipping lock prevents potential damage to the heads and discs that results from movement dur-
ing shipping and handling. The shipping lock automatically disengages when power is applied to the drive and
the head load process begins.
Cheetah 4LP drives decode track 0 location data from the servo data embedded on each surface to eliminate
mechanical transducer adjustments and related reliability concerns.
A high-performance actuator assembly with a low-inertia, balanced, patented, straight-arm design provides
excellent performance with minimal power dissipation.
Number of I/O
I/O circuit type
connector pins
single-ended
50
single-ended
68
differential
68
single-ended
80
differential
80
Number of I/O
data bus bits
8
16
16
16
16
5
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