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darkchen
July 16th, 2009, 03:55
iPlayer, a multi-media player on DS has been released for several days. A lot of people consider whether iPlayer could run a GBA emulator on DS. It is well know that running a GBA emulator on DS which is hard to be imaged before iPlayer release. Before iPlayer release people wish DS CPU is powerful enough to do that, but the CPU is not powerful enough to simulate GBA. Of course, Nintendo official have its solution, it is really not difficult to run GBA game on DS for official itself, but so far, it does not release any games fee paying downloading service yet, what is promised formerly. Further more, even though Nintendo official release GBA games downloading service, there will not be much too functions, such as screen shot, realtime save, frame skip, cheat and so on, what is included on common console emulators. PC emulator player should know these functions well.


Above all, I would like to introduce myself. I am not a professional programmer, but I am interested in programming. I pay a lot of attention on iPlayer news recently, and sent a mail to iPlayer official site to ask the possibility if GBA emulator could be launched by iPlayer, but unfortunately, according their reply, due to the copyright problems, iPlayer official will not provide GBA emulator. Yet, iPlayer really attract me, so I have bought one for researching.


In fact, simulating GBA is not very difficult. The principle is simple, using powered arithmetic capability to simulate a console circumstance, is similar to PC paltform console simulators. So to simulate GBA by iPlayer, the onboard CPU is indispensable. For a better effect of GBA simulating, the frequency of iPlayer onboard CPU have to be 20 times to GBA CPU, at least. Analyzing the ability of hardware decoding such high resolution videos, I suppose the onboard CPUís frequency is not lower than PSPís at least, even higher. Unfortunately, I have no detailed data about iPlayer, so these are just my hypothesize.


Logical analyzing:


The hardware of GBA includes two CPUs, one is a 32bit RISC instruction sets CPU (ARM7TDMI), which frequency is 16.78MHz, another one is 8bit CISC instruction sets CPU, a 130KB RAM, a 2D graphics card, six channel sound card, four channel DMA, four timers and so on. If count the GBA game card 256KB RAM on, the GBA system totally have 386KB RAM.


Then what we need to do is to simulate the hardware mentioned before. We must use our own instruction to simulate the ARM7 instruction system. On average, to simulate one instruction, need ten operations. In a word, iPlayerís CPU frequency must be ten times to GBAís, besides other hardware of GBA, there need to be another ten times. So totally twenty times, the iPlayerís frequency must be 340MHZ or higher, and there must be enough RAM. According to the ability of hardware decoding AVI video, I believe iPlayerís frequency will not be lower than PSPís CPU which is 330MHZ, and iPlayerís SDRAM should be 16MB or more, so running GBA emulator by iPlayer becomes possible.


Before writing, I mailed iPlayer official site again, wanting a SDK. I hope official will notice my post.