Active Protection System

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IBM Active Protection System

The Active Protection System

With the new series of ThinkPads IBM introduced the Active Protection System (APS) in 2003. The APS is a protection system for the ThinkPads internal harddrive. A sensor inside the ThinkPad recognizes when the notebook is accelerated. A software applet then is triggered to park the harddisk. This way the risk of data loss in case of when the notebook is dropped is significantly reduced since the read/write head of the harddrive is parked and hence can't crash onto the platter when the notebook drops onto the floor.

The whole concept of the technology seems very advanced. For the first part, the hardware sensor is capable of not only recognizing acceleration of the notebook, but also (to a certain degree) of its whole orientation in space, relative to gravity's axis. Furthermore, having the actual control put into software, its functionality is extendable and it gives chance to implement features like the "ignore minor shocks" feature which is present in the Windows based control applet. (This feature prevents the harddrive from parking in case of minor regular shocks such as occur when in a train or car.)

Linux Support

Linux support is in early development.

This feature definitely depends on software and there is no hardware or BIOS only way of making it work. A statement from IBM clarifies this: "The APS system will require APS software to be installed on the computer before it activates the harddrive parking . This means it will not work on systems preloaded with Linux."

IBM made contradictory statements about their willingness to release the specifications of the hardware sensor and its API to the linux community or some developers. Although a lot of developers and other interested people from the OpenSource community actively contacted IBM to get the specs, in fact they never got them.

Meanwhile, some independent projects are making progress:

  • Quoted from NewScientist.com: The latest Apple PowerBook laptops can be controlled with a gentle shake. Programmer Amit Singh has written code that lets him use the sensor to control software on the computer. The code is published at www.kernelthread.com/software/ams/.
  • The HDAPS project is dedicated to developing & testing a kernel module and a user space application.

Table of latch data from the (experimental) hdaps driver

ThinkPad bios firmware latch flip Value at 1.75 radians (see below) Value at 0.75 radians Value at rest boxers hdd-type
R50
R50p
R51 1VET64WW 01 reversed (110,75) (-36,-10) IC25N040ATMR04_0-ATA-DISK-drive
R52 01 reversed HTS541060G9AT00_SATA-DISK-drive
T41 01 reversed
T41p 03 OK
T42 01 reversed HTS548080M9AT00
T42p 03 OK
T43 01 reversed
T43p 03 OK
X40
X41
X41 Tablet 75ET30WW (550, 300) (410, 484) (480, 400) HTC426040G9AT00

For the value at 1.75 radians, and value at 0.75 radians, we want the data from the pivot application (included in the driver tgz) at SE and NW, with North being straight away from the user and West being to the left. In other words, SE is "tilt the laptop toward you and to the right" and NW is "tilt the laptop away from you and to the left".

Table of working / non-working drive firmware for the (experimental) hdaps driver park command

Drive firmware park command output
IC25N040ATCS04-0 CA40A71A not parked
IC25N040ATMR04-0 MO2OAD4A not parked
IC25N040ATMR04-0 MO2OADEA not parked
HTS548040M9AT00 MG20A5BA not parked
HTS548040M9AT00 MG20A5HA parked
HTS548080M9AT00 (TBA) parked
HTS541060G9AT00 MB3IA60A parked
HTC426040G9AT00 00P4A0B4
 ?  ?  ?

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