The following “letter to the editor” from Compaq's Western Research Laboratory relates to the recent announcement by ADS claiming the first sleep mode support for the StrongARM processor . . .

Dear Editors,

The article that you recently published, entitled ADS cranks down the power on StrongARM, contains a few inaccuracies. In particular, it fails to give proper credit for pioneering sleep modes on Linux handhelds (at least two prior implementations of sleep mode in Linux for StrongARM machines exist, and have been released to the open source community).

We [would therefore like] to correct the inaccuracies in the article. For your information, we have included some information on our Linux sleep mode implementation at the end of this message.

Thanks very much in advance.

Marc Viredaz
Deborah A. Wallach
Compaq Western Research Laboratory

Three years ago we developed sleep-mode support for Linux as part of the Itsy project at Compaq's Western Research Laboratory. To the best of our knowledge, we were the first to have such support for the StrongARM SA-11×0 series of processors.

We first implemented sleep mode for the Itsy in March 1998. Data on our sleep mode power consumption was informally presented at the Linux Expo
in May 1998, posted to the web the following month, and followed by an invited talk at the International Symposium on Wearable Computing in October 1998. At that time, our sleep-mode power consumption was 15mW on Itsy v1. On the latest version, Itsy v2, the sleep-mode power consumption is approximately
8.4mW, as reported in WRL Technical Note TN-57, October 2000, Power Evaluation of Itsy Version 2.3.

Our Linux source code was made public a couple of years ago. The latest published version, dated January 2000, contains the sleep mode code and is downloadable.

More information about the Itsy project is available here, or in our WRL Research Report 2000/6, October 2000, available here.

 
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