Some Questions...


kulak4

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Hi again.
I have some questions:
1. Why is there an option in PSX emu to overclock it to e.g. 300 if (at least mine) GP2X resets after setting to more than 250? How to accelerate it to more than that limit?
2. In dosbox emu README file there is written sth about source. Do I need to do that (a couple of things I'm not into) to make emu run? Without that it doesn't work.
3. One more hit about dosbox. A game is supposed to be in gpe format, but when I downloaded a freeware game, it doesn't have one (in opposite to e.g. Duke), only plenty of files...
4. What is the voltage for power supply adaptor? I have one with changable voltage, so that's why I'm asking...
5. Why don't batteries last for more than 2,5 h? When I check them with my recharge unit, it shows "good" status (it means almost perfect), but GP2X doesn't "care" - red light and "death" after the "welcome" screen...
Thanks in advance.
 

Squidge

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1. Various GP2X's are capable of various maximum clock speeds. The only way to determine the maximum of your unit is to try it. Also, sometimes running on an adaptor can give higher speeds than batteries. You can increase the speed typically by overvolting the processor (by modifying resistor values inside the unit) - however, this is not documented and WILL void your warranty.

3. Yes, GP2X games are supposed to be in GPE format. However, emulator such as dosbox may have its own demands (eg. typically requiring an extension of EXE for dosbox).

4. 3.3V Centre Negative 2A. 3V is good enough if thats all your adaptor will do. Higher amps is fine too, but if anything goes wrong, it stands more chance of more damage. If you accidentally use Centre Positive adaptor, you will fry the GP2X, so be careful. Also, make sure adaptor is regulated. Unregulated can damage GP2X.

5. GP2X is hungry, it requires heavy duty batteries. Your charger may say they are good, but under load they are not so good.
 

kulak4

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Thanks, but I don't see any reasons to miss the 2nd question. If you see any, this whole forum should be banned too.

I will ask it in a different way: do I need anything else than the dosbox emu downloaded from GP2X section to make it run?
 

Squirrel61

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Squidge said:
5. GP2X is hungry, it requires heavy duty batteries. Your charger may say they are good, but under load they are not so good.

Additionally, the GP2X has been designed to run off AA batteries, regardless if they're alkaline or rechargable. But Alkalines produce 1.5V where rechargables only produce 1.2V (rated voltage, freshly charged they might produce up to 1.4V). You might have noticed that freshly charged heavy duty batteries already produce a 2/3th battery gauge only after a few minutes of playing. That's because the whole power circuitry and measurement has been designed for 3.0V (=2x1.5V) and so the 2.4V of rechargables produces a too low voltage to keep the power converters inside the GP2X running.

That's also the reason why the GP2X runs more stable off external power, especially when overclocking. And it's one of the reasons I'm experimenting with the DS battery mod, because it's producing 3.7V opposed to the 2.4V of rechargable AA's.
 
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Squidge

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kulak4 said:
Thanks, but I don't see any reasons to miss the 2nd question. If you see any, this whole forum should be banned too.

What? The only reason I missed the second question is because I don't know the answer. I've not used dosbox myself, so I don't know how to make it run. Whats that got to do with banning the whole forum? :eek:
Squirrel61 said:
That's because the whole power circuitry and measurement has been designed for 3.0V (=2x1.5V) and so the 2.4V of rechargables produces a too low voltage to keep the power converters inside the GP2X running.

Well, the gp2x has a regulator that can increase voltage to an acceptable range with a wide variety of input voltages. However, the law is that lower voltage = higher current (W=V*A, and W only slightly increases), and the higher the current, the less the batteries last before they die. This is why a 3.7V battery is optimum (and decreases W slightly).
 
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juanvvc

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kulak4 said:
2. In dosbox emu README file there is written sth about source. Do I need to do that (a couple of things I'm not into) to make emu run? Without that it doesn't work.
Yes, you need a dosbox.conf file for each game, and a .gpe file (as you guessed) that calls to dosbox with your modified version of dosbox.conf. That is exactly the same thing that you need in dosbox for PC, you know, but in a PC you can use a general dosbox.conf and in the Gp2x you must configure the emulator for each game to take the best of the Gp2x hardware :)

There are some examples of configurations in this forum for emulated cpu freq, frameskip and keymappings. Check the documentation of dosbox as well. But be aware that dosbox in the Gp2x is really, really slow and you can only play very old games (pre-286, aprox)
 
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Squirrel61

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Squidge said:
Squirrel61 said:
That's because the whole power circuitry and measurement has been designed for 3.0V (=2x1.5V) and so the 2.4V of rechargables produces a too low voltage to keep the power converters inside the GP2X running.

Well, the gp2x has a regulator that can increase voltage to an acceptable range with a wide variety of input voltages. However, the law is that lower voltage = higher current (W=V*A, and W only slightly increases), and the higher the current, the less the batteries last before they die. This is why a 3.7V battery is optimum (and decreases W slightly).
I haven't studied the F100, but the main power converter in the F200 is most efficient at 3.7V. At lower and higher voltages, it's less efficient. Which doesn't mean that it isn't working at all. I haven't studied the characteristics of the other power converters in the F200 either.

But what I was mainly aiming at is that the battery gauge and other parts are designed to be able to handle 3.0V as an input voltage. At 2.4V, the battery gauge will simply show a lower value, even when the batteries are fully charged. And below a certain voltage, the power converters won't be able to produce their output voltage and the GP2X crashes or turns off. This point simply is reached earlier with a lower input voltage.

Some years ago, there where "rechargable alkalines", which where AA batteries that where rechargable but still produced 1.5V. I bet these kind of batteries would last much longer in a GP2X.
 
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