Subject: Re: Question
To: Andrew Gillham <>
From: Brendan Dowling <>
List: port-dreamcast
Date: 05/06/2001 18:06:03
On Sun, May 06, 2001 at 03:56:50PM -0700, Andrew Gillham wrote:
> Brendan Dowling writes:
> > 
> > No, it's not big enough to hold a kernel.  It's only 1 Mbit (128Kbyte) as
> > far as I know.  A 16X memory card (2 MB) could hold a kernel and a small
> > ramdisk image though.  But you probably wouldn't want to if you had the CD.
> Will the DC load/execute code stored on a VMU?  You could then save the
> ip slave loader and not need a CDROM at all. :-)

Nope.  There might be a possibility of getting the SH4 to boot from an 
external device hooked up to the bus via the expansion port in the same
way that the Playstation could boot from flash memory on the "parallel" 

But the VMU acts as a sort of "intelligent memory", meaning it has a CPU.  
It's a powered microcontroller device with some flash attached.  
The Dreamcast communicates with it via the Maple bus.   

Now, when the SH4 turns on, it vectors off to an area of memory in ROM.
This area of ROM contains code that reads more code from a disc and 
starts executing that code.  It doesn't attempt to read any program 
code from the VMU's (as far as we know).  So as long as we're not replacing
the boot ROM of the Dreamcast, then we have to use a CD to get our own code
running on the thing.  

Brendan Dowling