5. D.C distribution - separate twisted pair cable from each device to the
supplies
(as shown in four places). The wire size must be large enough to maintain a level
less than 10mV/ft drop.
2.7
Functional operations
2.7.1
Power sequencing
Applying
power to the drive can be done in any sequence. However, during
power-up, the WRITE GATE line must be held inactive or at a high level. This will
prevent possible "glitching" of the media.
After the application of
power, a 700ms delay should be introduced before any
operation is performed.
After power-on, the initial position of the read/write head is at Track 00. Because of
this, a recalibrate operation is not required.
2.7.2
Read operation
Reading data from the drive is accomplished by:
a. Activating the DRIVE SELECT line.
b. Selecting the head.
c. WRITE GATE being inactive.
The timing requirements for the read operations are shown in figures 2-6 and 2-7
repectively.
2.7.3
Write operation
17
2.0
m
s Nom
2.0
m
s Nom
4.0
m
s Nom
A
B
A
B
A
B
A
A
A
A
Read data
150 to 500ns
A = Leading edge of bit may be
±
400ns from its normal position.
B = Leading edge of bit may be
±
200ns from its normal position.
4.0
m
s Nom
4.0
m
s Nom
8.0
m
s Nom
A
B
A
B
A
B
A
A
A
A
Read data
150 to 500ns
A = Leading edge of bit may be
±
800ns from its nominal position.
B = Leading edge of bit may be
±
400ns from its nominal position.
Figure 2-6. High-speed read data timing (FM encoding 1.6Mb)
Figure 2-7. Low-speed read data timing (FM encoding 1.0Mb)
Leaflet No. 9419 26/4/97 6:10 pm Page 17
