I'm far from a nay sayer when it comes to the possibility for the Dreamcast on the Pandora. While it is
technically possible, but the likelihood of 100% compatibility and fullspeed is fairly slim.
The Dreamcast is essentially broken down into 4 subsystems
- The maple bus (joysticks, VMUs, anything that plugged into the front)
The SH-4 (16-bit instruction set, 32-bit RISC processor)
The AICA (the sound chip, includes a 45MHz ARM7TDMI core, 64 channel audio with hardware effects)
The PowerVR
The first section is easy, it can be emulated mostly passively and so long as whatever game you're using does not require VMU functions the impact should be minimal.
The critical point of the SH-4 is that, while it is slower, it includes a relatively high performance floating point unit. Depending on how good your DynaRec is in the emulator, and the performance of the OMAP3's NEON unit, this may or may not be an issue. The SH-4 has a narrow instruction set, it is minimal and has a similar number of registers as the ARM platform (16). The down side is that the SH-4 also includes a MMU which is used in all titles using the Windows CE layer. That makes dynarec slightly more complex.
The AICA is extremely powerful, and is thankfully underused in most cases. The core speed of this chip is 45MHz, and since the Pandora does not offer any form hardware audio acceleration this chip could easily cripple the system. If someone is feeling industrious and can offload this on the DSP, it should be negligible.
The big thing that everyone keeps quoting is that both systems use the PowerVR chipset. Yes, they use a similar chipset, but that doesn't change the fact that the Dreamcast not only had a dedicated memory space for video memory (unlike the OMAP's unified memory), we know very little about the OMAP3's actual stats. The Dreamcast also had full TDR, something that was sacked from future PVR chipsets (OMAP3's included) so there will be alpha fighting and possibly missing pixels. There is also the problem that there will be no low level API to Pandora's chip sets, leaving 3D performance at the mercy of the driver engineers.
Given all this, it should be theoretically possible to see some games running with Dreamcast emulation. Which games, and how fast they run is entirely up to the complexity of the game and how much work is put into the emulator itself. Don't except to see DOA2 any time soon.
