MD4331-d1G-MECH M-Systems Inc., MD4331-d1G-MECH Datasheet - Page 67

• Manufacturer Part Number: MD4331-d1G-MECH
• Description: Mobile Diskonchip G3 Data Sheet
• Manufacturer: M-Systems Inc.

or the autoexec.bat/config.sys files. Mobile DiskOnChip G3 can be used as the only disk in the
system, with or without a floppy drive, and with or without hard disks.
The drive letter assigned depends on how Mobile DiskOnChip G3 is used in the system, as follows:
•
•
If Mobile DiskOnChip G3 is used as the OS boot device when configured as drive C, it must be
formatted as a bootable device by copying the OS files onto it. This is done by using the SYS
command when running DOS.
9.3
9.3.1 PC Architectures
In current PC architectures, the first CPU fetch (after reset is negated) is mapped to the boot device
area, also known as the reset vector. The reset vector in PC architectures is located at address
FFFF0, by using a Jump command to the beginning of the BIOS chip (usually F0000 or E0000).
The CPU executes the BIOS code, initializes the hardware and loads Mobile DiskOnChip G3
software using the BIOS expansion search routine (e.g. D0000). Refer to Section 9.2 for a detailed
explanation on the boot sequence in PC-compatible platforms.
Mobile DiskOnChip G3 implements both disk and boot functions when it replaces the BIOS chip.
To enable this, Mobile DiskOnChip G3 requires a location at two different addresses:
•
•
This means that the CS# signal must be remapped between two different addresses. For further
information on how to achieve this, refer to application note AP-DOC-047, Designing DiskOnChip
as a Flash Disk and Boot Device Replacement.
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If Mobile DiskOnChip G3 is used as the only disk in the system, the system boots directly from
it and assigns it drive C.
If Mobile DiskOnChip G3 is used with other disks in the system:
o
o
After power-up, Mobile DiskOnChip G3 must be mapped in F segment, so that the CPU
fetches the reset vector from address FFFF0, where Mobile DiskOnChip G3 is located.
After the BIOS code is loaded into RAM and starts execution, Mobile DiskOnChip G3 must be
reconfigured to be located in the BIOS expansion search area (e.g. D0000) so it can load the
TrueFFS software.
Boot Replacement
Mobile DiskOnChip G3 can be configured as the last drive (the default configuration). The
system assigns drive C to the hard disk and drive D to Mobile DiskOnChip G3.
Alternatively, Mobile DiskOnChip G3 can be configured as the system’s first drive. The
system assigns drive D to the hard disk and drive C to Mobile DiskOnChip G3.
Data Sheet, Rev. 1.0
Mobile DiskOnChip G3
91-SR-011-05-8L