The Fans Dreamcast

[Athiril]

Yep, SH6 sounds good, more memory, upgrade the video chip too.

900MHz SH6
256MB+ Ram
better video chip

I'm sure the BIOS doesn't need to support the extra features on the video chip to use them etc, like a pc.

Then you could have Dreamcast Enhanced, so people/companies could make better commercial/homebrew games, port over some PC games, Ogre3D engine on DC would be nice - http://www.ogre3d.org/

Still have the prob of 640x480.... though I'm sure you can interface with the hardware directly, some of us could experiment with it, provide an interface library for setting higher modes etc, would be very nice..

I mean the X-Box was enhanced by a third party with a Tualatin 1.4GHz Celeron (256KB L2 cache), from the 700mhz processor they had, I think they put more mem and upgraded the vid, but not sure...

edit: http://www.hitachi-sk.co.jp/Products/SH-C/HomePage.html

I wonder if we could use the SHC C/C++ compiler to compile for the SH4 in the dreamcast

[Athiril]

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...

=======================================
To make this clear:

Modifed DC specs so far

SH-6 900MHz
16MB+ 175MHz PowerVR3
64MB - 256MB memory

[Athiril]

GOOD NEWS
"This is a series of 32-bit microprocessors which incorporate the SH-4A, the high-end CPU core in the SuperH Family. The SH-4A instruction set is fully SH-4 upward compatible"

from http://www.renesas.com/fmwk.jsp?cnt=...sh7780_series/

check this out:
http://www.renesas.com/fmwk.jsp?cnt=.../sh7780_group/

at least we able to upgrade it from 200MHz, to 400MHz, doubling the clock rate, faster than the PS2

DC uses 100MHz SDRAM modules I think, I will have to look up the chips it uses when mine decides to get here :P, so the SDRAM idea is still there

So is the PowerVR3 and more video memory idea.

If I ever get this done, I could port Ogre3D to DC, and we could have extremely high quality graphics games, just check out http://www.ogre3d.org/ and check out the screen shots.

[quzar]

Do you understand that the newer SH processors while being backwards compatible in their instruction sets, are physically different? Basically, even though you could run the same code on both, you wouldnt be able to fit this in the DC without actually making your own PCB with all the DC parts on it, in essence simply creating a while new machine that could also possibly play DC games (i assume though that doing something like this would break many games since they were designed to run on the dreamcast, not whatever it is you are trying to make)

[Eric]

Well Atheril that looks like amazing news. I do have to say in a much better form that you will probably have to build a whole new maching which isnt much of a problem do to people modding there systems in bigger boxes and doing weird things.

But the thing about making it work with games i would suggest if you have a lot of money to try this out and test one game and see if it works. If it does show some images of it working on the tv and also a pic of your new dreamcast.


Eric

[Athiril]

Actually, it wont take up any more physical size, it should all work, if there are physical non-micro physical differences between the SH-4 and the SH 7780, then we could use some sort of socket adapter, just like the Socket 370-T adapter for socket 370 motherboards that did not support tualatin cpus, etc.

Apparently we also need the last 4 numbers of the checksum of the BIOS, for when the cpu is produced :/

Unfortunately I am not the rich bastard I'd like to be

A more feasible solution is making a DC-PC, which could be a version of Linux, that would load up DC cds automatically, and play them etc, and we could provide a "Dreamcast Extensions" format, to support use of more RAM, video memory, and a "faster" core cpu etc, support use of a hard drive.

meh...

[quzar]

[quote author=Athiril link=board=hardware;num=1092771617;start=15#15 date=08/30/04 at 05:06:53]Actually, it wont take up any more physical size, it should all work, if there are physical non-micro physical differences between the SH-4 and the SH 7780, then we could use some sort of socket adapter, just like the Socket 370-T adapter for *socket 370 motherboards that did not support tualatin cpus, etc.[/quote]

you dont seem to realize that the CPU in the dreamcast is not attached to it through a socket, and was not intended to be upgraded nor would any other SH processor be socket based. The processor in the Dreamcast is directly attached to the pcb.

[Athiril]

Dont make assumptions regarding me, ever >

All you need is to know the differences in the pins on the two cpus, have a socket made up to your specifications with pins, and solder it in place of the SH-4 on the DC board.

[quzar]

usually setups like that cant be soldered on. the processor would be embedded when the PCB is printed (afaik). Without extremely precise professional grade equipment it would be impossible to do, and even given that equipment it would take a user withlots of experience and skill. The only way i could think of this working as a homebrew mod would be to break off the SH-4 (very carefully =P) then use the pins for wires that would attach to the new processor's pins. That way you have room to add whatever you will have to to compensate for the fact that they are two different physical processors.

If you go over to DCemulation.com and search in the hardware section you will see a topic i started about well, almost two years ago with similar thoughts. At that time i spoke to a representative of rensas(sp?) and asked many questions about their use of the terms backwards compatability and the form factors of the chips. I also found out some information that i believe is undocumented, which includes the fact that there were more than one version of the (custom) SH-4 processor that was in the Dreamcast. And iirc 3 different versions of the pvr chip.

I really hope i didnt insult you, as you seemed angry in your last post. I am simply trying to give you information that you may or may not already have.