Recording Methods; Physical Specifications; Figure 4. Read/Write Timing - Seagate ST251 Product Manual

1.13 TYPICAL DRIVE TIMING
This section details typical ST251/251 R/277R timing. Refer to the
Seagate ST412 Interface Manual
for a general treatment of drive tim-
ing.
FIGURE
4:
Read/Write Timing
• DRIVE SELECT
I..
ooj((
jj~ ---------
1.4 FUNCTIONAL SPECIFICATIONS
ST251
ST251 R
ST277R
\>
Rotational Speed:
3,600 RPM
±
0.5%
(
(
Recording Density:
9,935 BPI 14,902 BPI 14,902 BPI
18
Flux Density:
9,935 FCI 9,935 FCI 9,935 FCI
Track Density:
777 TPI 777 TPI 777 TPI
Interface:
ST412
ST412
ST412
Recording Method:
MFM
RLL (2,7)
RLL (2,7)
Data Transfer Rate:
5.0 Mbits/sec. 7.5 Mbits/sec. 7.5 Mbits/sec.
- HEAD SELECT
1.5 RECORDING METHODS
1.6 PHYSICAL SPECIFICATIONS
The ST251 is designed to operate with the ST412 interface with MFM
encoding at 5.0 megabit/sec. data transfer rate.
Caution: Operation of an MFM drive with an RLL controller is not ap-
proved by Seagate.
1.63 inch. max. (41.4 mm)
5.77 inch. max. (146.1 mm)
8.00 inch. max. (203.2 mm)
2.75 Ibs. (1.25 Kg.)
The ST251R and ST277R are designed to operate with the ST412 in-
terface with Run Length Limited (2,7) encoding at 7.5 megabit/sec.
data transfer rate.
Height:
Width:
Depth:
Weight:
(
~
I (
i ~
,~,
(
(
I ((
--------------j"'j"----------
H
J
L
40 nsec. min. /95 nsec. max. 8 !lsec. max.
I I
(Head Switching)
n n
n n
n n n
+
MFM (RLL) VALID
I U U U I ~
U
Q~O~
-R-E-A-D-D-A-T-A---1-
~ ------..,: -1 ~
8 !lsec. max.
200 nsec. (write/read
(typ. bit cell) recovery)
-.-W-R-IT-E-G-A-T-E-------I ..,~
400 nsec. max.
H ) ~
r-
50 . 150 nsec.
+
MFM (RLL) WRITE DATA ~~ •• _
U
J
L
200 nsec.
I
r
(typ. bit cell)
1-14
ST251 /251 R/277R Product Manual, Rev.A
ST251 /251 R/277R Product Manual, Rev.A
1-3