MD3331-D32-V3Q18 M-Systems Inc., MD3331-D32-V3Q18 Datasheet - Page 38

• Manufacturer Part Number: MD3331-D32-V3Q18
• Description: Mobile Diskonchip Plus 128Mbits 1.8V I/o
• Manufacturer: M-Systems Inc.

The drive letter assigned depends on how Mobile DiskOnChip Plus is used in the system, as follows:
8.3
8.3.1 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 Plus software using the BIOS expansion search routine (e.g. D0000). Refer
to Section 8.2 for a detailed explanation on the boot sequence in PC-compatible platforms.
Mobile DiskOnChip Plus implements both disk and boot functions when it replaces the BIOS chip. To enable this,
Mobile DiskOnChip Plus 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.
8.3.2 Non-PC Architectures
In non-PC architectures, the boot code is executed from a boot ROM, and the drivers are usually loaded from the
storage device.
When using Mobile DiskOnChip Plus as the system boot device, the CPU fetches the first instructions from the
Mobile DiskOnChip Plus Programmable Boot Block, which contains the IPL. Since in most cases this block cannot
hold the entire boot loader, the IPL runs minimum initialization, after which the Secondary Program Loader (SPL) is
copied to RAM from flash. The remainder of the boot loader code then runs from RAM.
The IPL and SPL are located in a separate (binary) partition on Mobile DiskOnChip Plus, and can be hardware
protected if required.
For further information on software boot code implementation, refer to application note AP-DOC-044, Writing an
IPL for DiskOnChip Plus 16MByte Devices.
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Boot Replacement
If Mobile DiskOnChip Plus is used as the only disk in the system, the system boots directly from it and
assigns it drive C.
If Mobile DiskOnChip Plus is used with other disks in the system:
o
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If Mobile DiskOnChip Plus 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.
After power-up, Mobile DiskOnChip Plus must be mapped in F segment, so that the CPU fetches the reset
vector from address FFFF0, where Mobile DiskOnChip Plus is located.
After the BIOS code is loaded into RAM and starts execution, Mobile DiskOnChip Plus must be
reconfigured to be located in the BIOS expansion search area (e.g. D0000) so it can load the TrueFFS
software.
Mobile DiskOnChip Plus 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 Plus.
Alternatively, Mobile DiskOnChip Plus can be configured as the system’s first drive. The system
assigns drive D to the hard disk and drive C to Mobile DiskOnChip Plus.
Data Sheet, Rev. 1.7
Mobile DiskOnChip Plus 16/32MByte 1.8V I/O
95-SR-000-10-8L