IBM DTTA-351010 - Deskstar 10.1 GB Hard Drive Specifications page 166

When the automatic power down sequence is enabled, the drive will enter Standby
mode automatically if the timeout interval expires with no drive access from the host.
The timeout interval will be reinitialized if there is a drive access before the timeout
interval expires.
158
O E M Specifications for DTTA-3xxxxx
Value Timeout
----------- ---------------------------
0 Timer disabled
1 - 240 Value * 5
241 - 251 (Value-240) * 30 minutes
252 21 minutes
253 8 hours
254 21 minutes 10 seconds
255 21 minutes 15 seconds
seconds