Dreamcast Hard Drive

[Dull Blade]

you can make it faster. You can overclock it, it boost the speed from 200mhz to somethink like 233mhz. but to do thant you need find some chip, and I've looked but never found. As for VMU HDD, some one might be able to do that, but I'm not sure how fast the DC can read or write to a vmu. It might end up being dreadfully slow.

[Abobora]

So, any news on this? I've been thinking about it, and if we could connect an flash card, or Hdd, it would be awesome for my Portable DC project.

[reliantkcar]

ok i've looked all over the internet and alli found was this picture bu don't click on it the sites dead

http://images.search.yahoo.com/searc...p=mss&ei=UTF-8

[Morph]

you can make it faster. You can overclock it, it boost the speed from 200mhz to somethink like 233mhz. but to do thant you need find some chip, and I've looked but never found. As for VMU HDD, some one might be able to do that, but I'm not sure how fast the DC can read or write to a vmu. It might end up being dreadfully slow.

The 'chip' you are referring to is a crystal oscillator. The speed of the oscillator determines how fast you are clocking your Dreamcast. I've done the mod several times, and doing do is well documented both here and at dcemulation.

When you are overclocking the DC, you are boosting the entire speed of the system, not just the CPU and GPU. For instance, using a 45MHz crystal oscillator would be multiplied by 3 over the entire bus, giving a rough 133MHz~ FSB speed (a boost of 33%). So, your entire Dreamcast is now moving 33% faster, not just the CPU and GPU. Just to demonstrate, the the maximum data the memory on the DC can push at 100MHz is 800MB/s. Running it at 133MHz produces an increased bandwidth limit to 1024MB/s (effectivly 1GB/s).

[DreamDogg]

If someone's got a logic analyzer and is willing to reverse engineer the interface protocol, it could lead to homebrewn cdrom interfaces.

Logic Analyzers run ~$300 and up on eBay. The Intronix LogicPort analyzes 34 channels for $389

http://www.pctestinstruments.com/

Is there a cheaper way to analyze the signals, and does anyone here have the skills ?

[DreamDogg]

Lower-cost Logic Analyzer for $169.50...

http://www.hobbylab.us/

It's USB based and comes with a 2-channel oscilloscope, too!

Anyone else interested in exploring the Dreamcast's GD-ROM bus ?

[MrSporty]

I have hooked up my own LA (A ZLGLogic 32 chan) to a GDROM drive and have plenty of data regarding the commands , data and transfer types.

One of the main things holding up my progress is an undocumented set of commands, packets commands 0x70 and 0x71.

I have a suspicion of what the commands are but ANY further info would be greatly appreciated.

[quzar]

There's a chance it could be Seek. The GDRom SPI command system in part implements ATA specifications/commands. ATA-1 has 7xh as an undefined 'seek' command. ATA-2 clearly defines 70h as seek. 1Bh is defined in the SPI as Seek, but some of the other commands have redundancies.

Nathan Keynes, the author of lxdream, thinks that 70h is the spinup command, but is not sure, and knows that 71h is common, but does not know what it does.

Hope that helps.

[MrSporty]

My suspicion is that the 70/71 pair relate to the security ring present on pressed GDROM's.

The 70 is likely a "Seek to and Read Ring" command.

The 71 then responds with a variable length response which as N.K pointed out , appears as random data. From my logs , altho the length is variable it doesn't seem to change from between 1900-2040 bytes.

My assumption is that the data is a scrambled representation of the security ring data with the length dictating the scrambling seed or method.

I asked drkIIRaziel (NullDC) and he greatfully modded his emu to return random data instead of the fixed block that most DC emus are returning for the 71 command and he reported that it caused random errors when trying to boot images. Some would boot , some would appear to boot then reboot and some would just fail entirely.

This wasn't exactly as i imagined because if the 71 response was solely protection related then you would expect a fake reply to fail all the time.

[ExcruciationX]

Hmm, it would be awesome to have a hard drive on Dreamcast.