Posted on 2003-12-03
In the application note (AP044) from Msystems diskonchip it is given as:
"The DiskOnChip Millennium is mapped into an 8KB memory window in the host platform’s
memory map. This 8KB window consists of four 2KB windows." Why is this mapping done?
Is this done for all the DiskOnChip Millennium?
The steps for BIOS is summarised as
1. After DiskOnChip Millennium BUSY# signal is negated, the CPU fetches the Reset Vector from
the Boot-Block area, fetches the Boot Code stored there, and starts to execute the code.
2. Boot Code runs the first part of BIOS, initializing the basic hardware functionality.
3. Boot Codes loads the rest of the BIOS from the flash memory to the DRAM, and transfer control
4. Chip Select of DiskOnChip Millennium is remapped from Reset Vector to BIOS expansion area.
5. CPU executes the rest of the BIOS code, including ROM expansion devices (among them, the
DiskOnChip Millennium itself).
6. CPU calls OS bootstrap loader (INT19).
7. OS is loaded, and recognizes the DiskOnChip Millennium as the boot device.
8. OS loads the application code from the DiskOnChip Millennium and executes it.
9. Application software uses DiskOnChip Millennium exactly as if it were using a regular hard disk.
In step 4 why is this remapping done?