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 Thinkpad's 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 clearifies 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/.

• There is a fairly detailed article about reverse engineering the APS accelerometer interface by Mark Smith from IBM Research. Apparently they even have a prototype Linux driver working, but cannot release the full source yet.

• 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	boxers	hdd-type
R50
R50p
R51	1VET64WW	01	reversed				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

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, NW is "tilt the laptop away from you and to the left" and SE is "tilt the laptop toward you and to the right".

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
?	?	?

Related Links

• IBMs ThinkVantage™ Technologies Flash presentation - Active Protection System
• HDAPS project page
• HDAPS-devel list archive

Models featuring this Technology

• ThinkPad R50, R50p, R51, R52
• ThinkPad T41, T41p, T42, T42p, T43, T43p
• ThinkPad X40, X41, X41 Tablet