HP Forum Archive 08

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DOUBLE SPEED hp49g ? Message #1 Posted by olivier croissant on 30 May 2002, 1:53 p.m. I see on Ebay.de and on www.cynox.de that it is possible to double the speed of a hp49g. Is this real ? How do they do that, I thought that it was impossible to open a 49g without destroying it? oliiver

Re: DOUBLE SPEED hp49g ? Message #2 Posted by Tom (UK) on 31 May 2002, 3:42 a.m., in response to message #1 by olivier croissant Yes, they double the clock rate to the CPU with internal modifications, I think the high speed can be turned on and off by the user. I think the higher clock rate is 8MHz - still slow compared to alot of modern stuff. However this doubles the battery consumption and some calcs may not work above room temperature (20'C). I don't know how they open the HP49G but if they have had a few broken ones to experiment with they probably know what they are doing. Tom.

Re: DOUBLE SPEED hp49g ? Message #3 Posted by Jonathan Busby on 1 June 2002, 1:46 p.m., in response to message #2 by Tom (UK) Tom said : "Yes, they double the clock rate to the CPU with internal modifications, I think the high speed can be turned on and off by the user. I think the higher clock rate is 8MHz - still slow compared to alot of modern stuff." This is not quite correct. The clock speed is actually only increased from 4 MHz to 6 MHz via a new crystal with a faster clock rate. The calc can be switched from normal to "double-speed" (which is kind of a misnomer it seems) mode by holding down the on key. (they install a small microcontroller I believe) As far as I know, the maximum speed at which the 48/49 cpu (actually the Yorke IC) can be clocked at is somewhere around 6 MHz. After that it stops functioning. There are however other ways of overclocking the Yorke that could result in higher achievable speeds and lower power consumption. See http://groups.google.com/groups?hl=en&lr=&selm=kpgmbu0ldjjgkgbfe6it2a6cpcntibleqo%404ax.com&rnum=2 . To the best of my knowledge no one has tried this method though. ------------------------------------------------------------------------------------------------------------------------ Remove the random permutation of "NOSPAM" from my e-mail address before replying.

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