Quantum Q250 User Manual

2.2.7
12 VOLT SUPPLY-Q200 START CURRENT PROFILE (TYPICAL AVERAGE)
........ , , ,
2 . 0 - -- - -- -- - ~~~ - ~- -~ aT R --- --r --- -- -- - ~- - -- -- - --
.~ lP 0 SP EO :
112 (A) ;\ I ..,
: : \ t : I
1 . 0 -r- - ~-:-: - ~~~~~ ~ ~~ --M -- ---- --j-- - -- --~f - -- -- - --
o
~ L leU.e POR ~
i
t-o, poweron
: j r 7 IL Jt
IV • .j..~
I
I
10
15
SECONDS
TYPICAL SEEK
CURRENT. t=3-40 MS
Figure 2-8: Drive startup Current Profile
Shorting Plug options
Figure 2-9 is a top view of the PCB, showing the locations of shorting
plugs, terminators, and connectors.
SCSI Bus Device Address
Three shorting plugs A2, A1, and AO, determine the unique address (0-
7) assigned to each drive. The address determines the priority level
of each device and therefore which device wins arbitration if several
devices are contending for the SCSI bus simultaneously. Highest pri-
ority is address 7, usually given to the host, and lowest priority is
address o. The three plugs establish a 3-bit binary number with the
following values: A2 = 4, A1 = 2, AO = 1. with no plugs inserted,
the address is 0; with all 'plugs inserted, the address is 7. Drives
are shipped with plugs in A2 and A1 (address 6).
Enable Parity (EP)
When shorting plug EP is installed, parity checking of data across the
SCSI bus is enabled. with EP removed, parity is not performed. The
use of parity is a system option. See the description of signal -
DB(7-0,P) in Section 2.2.4 for additional information.
Drives are shipped from the factory with parity enabled (plug EP
installed) .
2-16

Quantum Q250 Specifications

General

Brand	Quantum
Model	Q250
Category	Storage
Language	English