I have my suspicions, that a PowerVR2 in the Dreamcast is a Kyro chip, or rather, Kyro used PowerVR2's, so maybe we could get hold of the best Kyro produced, and replace the video chip with it etc, i'm might experiment with that in the future, getting hold of an SH5 or SH6 (i think SH7/8/9 use 64-bit addressing, so would not be compatible), and mod that onto a DC instead of the SH4, see if it works...then procede with a PowerVR2 -> Kyro replacement...
Anyway, I'll have 3 or 4 dreamcasts eventually (few more days till i have my first one), 2 will remain unmodded, fo gaming, developing, and network/lan testing, one will be faulty that i'm going to get for cheap sometime, for a mod like an mini-itx motherboard mod (or maybe i can use my saturn I destoryed...).., and the last one for modding the hardware with newer hardware etc..
a quote - "November 21, 200064Mb KYRO based Videocard - Hilbert Hagedoorn @ 12:03
I stumbled into some product information from PowerColor over at Akiba's. It seems that the awaited Evil Kyro, PowerVR3 based, has hit the shops and is equipped with a luxury 64MB memory"
http://www.firingsquad.com/hardware/...ro/default.asp there are some more quotes there
so it's a possibility to mod it with a Kyro or Kyro II chip, perhaps an even faser chip..., the core just by itself may work, we could replace the bios too, that might help a bit, or may not work... dunno if you could replace the memory on the DC circuitry, you would have to if you replaced the video bios..., so if we could do all three: core + video bios + memory
That would be the CPU, and Video and Video memory taken care of, we'd just be left with system memory, which suprisingly, should be the easiest to do, we just need to find out all the info on the current memory modules, and replace them with compatible higher-capacity memory modules.
If all that works out, we have our new high performance Dreamcast ^_^
I'll do some digging around, see if I can find more info that would be helpful in doing this.
"Specs
12 million transistors
0.25 micron process
125 MHz core / memory clock
64 MB SDRAM
2 Pixel Pipelines
250 megapixel/s fillrate (750 megapixel/s equivalent fillrate)
128-bit data path to memory (2GB/s bandwidth)
32-bit z-buffer
Tile rendering architecture
Full Scene Anti-Aliasing (2x and 4x)
Environment Mapped Bump Mapping (EMBM)
8-Layer Multitexturing
Motion compensation support
Support for AGP 4X, SBA, DiME
DXTC Texture Compression
Full OpenGL ICD
270 MHz RAMDAC"
Kyro I specs, 125MHz gpu, i think the actual core replacement would certainly be compatible, DC PowerVR2 is 100MHz isn't it?, +25% core speed aint too bad, let me see if I can find a faster one...
edit: Kyro II chip is 175MHz, that would be quite nice in a Dreamcast, it's also TBL (tile based rendering), thus a PowerVR chip, and should be compatible, I'm currently getting a Kyro 64MB card for very cheap ^_^, the Kyro II, is almost equal to Geforce 2 GTS performance, so in 640x480 on the DC, it would be very nice.
Okay, the Dreamcast motherboard looks like (sorry, haven't got my DC yet!, it's on it's way though) http://entertainment.howstuffworks.com/dreamcast2.htm , from this picture, it looks like there are 4 memory modules, and 2 video memory modules, there are 8 memory modules on the Kyro II video card, each 8MB each, if they are the same, we can upgrade the Dreamcast to 16MB (or more if we can get memory from elsewhere), it does kinda work like this, as I remember having an old pic video card, with memory sockets to upgrade the memory in it, I pulled out memory from an old something or other, same size modules, and used them they worked, but they weren't the actual chips it was supposed to use, went from 1MB to 4MB , oh yeah, with the Kyro II chipset, 16-bit modes will look like 32-bit modes, due to it's 'magic'
So far we have
Dreamcast "Enhanced"
SuperH 4 64 bit RISC 200MHz -> SuperH 6 64 bit RISC 900MHz
128 bit Hitachi PowerVR2"DC" 100MHz -> 128 bit Hitachi PowerVR3 "Kyro II" 175MHz
I dont know the speed of the memory on the Dreamcast, so lets say we'll use PC150 for now
8MB Video Memory -> 16MB Video Memory (we may even be able to use memory modules from PC133 or PC150 SDRAM, Kyro II video memory is 175MHz though 5ns (which is 200MHz, but is clocked 175MHz on the Kyro II), So perhaps DDR400 memory modules (which is just PC-200 when you take it off the controller, I *think*)
16MB system memory -> 64MB (4x16MB modules should be from 128MB PC150, SDRAM has 8 memory modules) or 128MB (4x32MB modules - should be from 256MB PC150), so by getting a 512MB PC150 or possibly DDR400 (PC200) module (prob get away with PC133), we can have 256MB ram
It sounds quite possible to me!
edit: the SH4 has a bus of 100MHz, so no more tha PC100 should be needed, however, it depends on what the SH5/SH6 or newer have, we must even consider that the bus could default to 100MHz, thus underclocking it, if the bus was greater than 100MHz...
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To make this clear:
Modifed DC specs so far
SH-6 900MHz
16MB+ 175MHz PowerVR3
64MB - 256MB memory
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