HP-48G+ with RAM extension & increased speed


Hi altogether!

I consider getting an HP48G+ with internal RAM-extension (1-2 MB) and a Speed-Module which is said to increase
Prozessor speed about 30-40%. My concern is that 1. the increased Processor speed will harm the Saturn in the
long run and 2. the Module + internal RAM-card would force draining of the batteries considerably. Does anyone
has any information or even experience on this?

Regards, Jürgen (HPCC #1065)


Hi Juergen, I have been using a HP48GX1280Sp quite a while and can only see two drawbacks 1) Battery consumption (in my unmodified HP48GX I change batteries very seldom, while the overclocked HP48GX1280Sp more or less "eats" batteries. If this is due to the overclock or that the memory is not having the same low consumption as HP RAM card memory, I don't know). 2) The clock gets out of sync, but I have never used the clock so that is less of a matter to me.

Best regards,
Erik Ehrling

(Remove NO-SPAM from the email address before using the email address)


Hi Erik!

Thanks a lot for your input! The info of the effect of speeding up the machine on the system clock is particularly valuable to me! Just for your info: I'm using a 512KB card by Cynox (Germany) in my HP48GX (normal speed) and there seems to be no (significant) draining of the batteries. So, I guess, the machines hunger for batteries is mainly due to the overclocked CPU ... I'm not sure on this, however ... Thanks again!



The power consumption of a CMOS circuit generally scales in direct proportion to the clock rate. Boost the clock 50 percent, power goes up 50 percent. I suspect if a modified machine really eats the batteries it is caused by the RAM chips. If any input or bidirectional pin on a CMOS chip is left floating, that one pin can cause the chip to draw a HUGE amount of power.


Thanks! If I understand you right, you suspect that the increased power consumption is almost only due to the RAM-card installed. Well, might be that my experience is based on faulty "experiment-assumptions" (not using the HP48G+ with card installed "equally" to that without card, that is). However, perhaps I'll sacrifice a set of batteries in order to conduct a reliable experiment sometime :-) I'd let you know then ...


"the increased power consumption is almost only due to the RAM-card installed"

I've always read in comp.sys.hp48 that the "speed module" is the guilty in this story, but I have not electr. knowledge...
I have a GX with two cards (128kb and 1Mb) and the battery consumption is about three months with normal use



Thanx for dropping in! I'll try to check comp.sys.hp48 for the information you indicated. As for the note on the use of the HP48GX with cards: Well, OK, but the plug-in cards do have individual power supplies (at least, this is true for the cards by "Cynox" that I use) don't they? So, they shouldn't affect the calcs batteries at all?


Well... you are right in a part: the card battery feeds the card when the calc is OFF, so only when I use the calculator, the main (system) batteries are feeding the extra RAM.


I forgot... Looking in comp.sys.hp48 you'll find a post of VPN saying that the speed increase is not great... I can't remember exactly what he said, but I remember that after reading I thought it is not worth. Perhaps a standard GX with Klot's RAM cards is cheaper.




Hi Raul!

Many thanks again for your comments! I haven't been aware that the cards batteries aren't feeding the card when the calc is on; new information to me -thanks! Also, I'll try to get the info on the realistic speed increase you mentioned so as to overthink my decision. Maybe you're right that an HP48GX with Klots RAM cards would be cheaper, maybe an HP48G+ with extra memory but without Speed Module is the best choice ...

Have a nice weekend, Juergen

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