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Q: Virtually none of my MAME ROMS are working. I've got the latest versions. 

A: You need MAME ROMS which are compatible with MAME 0.37b5. This is a relatively older 
version. Many of the later version MAME roms will not work. Some ROMS can be easily converted 
(using freely available tools), others cannot. 

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Q: Why isn't Neo Geo game 'X' not working?

A: Currently, it's not included. Will be added later when more memory becomes available.
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Q: Why port MAME 0.37b5 and not some later version?

Later versions of MAME tend to concentrate on compatibility as the cost of performance. 
Earlier versions are more in line with the hardware capabilities of our target machine - 
in this case the Dingoo. These earlier versions have some significant programming speedups 
which have been removed in later versions. Two examples are the use of internal 8-bit graphic 
rendering and dirty buffer handling.

Later versions of MAME with ALL the drivers included can easily reach a size of 40-60MB - 
more than the amount of RAM available to the Dingoo (which is 32MB).

So basically we're talking trade-offs here.

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Q: The game fails to start. 

A: Large games may exceed the Dingoo's memory limitations. Even some "smaller" games 
may fail to load. For example xmen.zip uncompresses to 9MB. MAME then needs to decode the 
graphics - often doubling the size of the graphic ROM areas. MAME also needs to allocate 
runtime memory to the emulated machine's hardware. This can vary enormously but sophisticated 
hardware often needs a lot of RAM again. There is no solution to this at the moment, though 
I have some ideas.

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Q: My game fails to start. I don't think size is the problem.

A: Okay, it may be a bug. Let me know on the forums.

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Q: How do I set the volume?

A: Press SELECT+B to get access to the volume/screen menu. UP and DOWN change the volume 
component and LEFT and RIGHt set the desired level.

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Q: The game runs slowly. It runs fine on the GP2X or Wiz (or some other handheld).

A: The GP2X/Wiz have a very nice selection of assembler-based libraries. In particular Cyclone
 and DrZ80. This can speed up games which use the M68000 and Z80 CPUs enormously. When the game 
 starts up, an information screen describes the hardware. If there are M68000/Z80 CPUs on this 
 list, this may be the problem. There possibly faster cores available for the Dingoo, I will 
 investigate for future releases.

There are two ways of increasing the running speed of a game:

(1). Switch off the sound from the Game Selector menu before launching the game.
(2). Increase the Dingoo MHZ speed from the default 336Mhz.

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Q: Why can't I see the entire game screen?

A: The hardware being emulated varies enormously. Some hardware has screen resolution which 
exceeds the Dingoo's 320x240 screen resolution. As a result, you can't see the entire game screen 
at once. Scaling the game screen to fit into the Dingoo's screen will solve this problem. Try using 
one of the scalers: Scale Best, Scale Fast or Scale Half. This can be combined with 8-bit/16-bit video 
options to increase quality at the cost of speed.

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Q: What's the underclock option for?

A: First a bit of theory:

Arcade machines have CPUs which are generally faster than they really need to be. For example, 
CPS1 machines have M68000 CPUs clocked at 10Mhz.
When the game is running, it may only use 7Mhz worth of instructions, the rest of the time the 
machine is literally doing nothing - waiting for the next screen refresh.
MAME (and other emulators) faithfully reproduce this behavior including the needless "waiting around".
 By under clocking the emulated CPU (to say 8Mhz), MAME has (20%) less work to do emulating the CPU 
 which can be used in other areas - generally rendering more video frames.
Under clocking is purely experimental on the user's behalf. As a rule of thumb, underclocking to 80% 
is pretty much okay. 
Some games will not work as they rely on precise timing - usually based on the speed of the CPU. 
Modifying it's speed will result in the game not running as intended or worse, not at all.
No harm can come from under-clocking - except for the game not working.

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Q: What the CPU Cores option for?

A: Currently this does nothing. The idea is that alternative M68K and Z80 CPU cores will be available
 that provide a faster emulation than the current compatible (but slow) versions used by default in MAME.
The GP2X version of MAME4ALL has options for Cyclone (M68K) and DrZ80 (Z80) however these are specific to
 ARM CPU. The A320 Dingoo uses a MIPS based CPU.
There are faster 'C' based M68K and Z80 CPU code out there - I just need to integrate them in. 

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