MD3331-D64-V3 M-Systems Inc., MD3331-D64-V3 Datasheet - Page 50

• Manufacturer Part Number: MD3331-D64-V3
• Description: Diskonchip Millennium Plus
• Manufacturer: M-Systems Inc.

Table 6 shows the active data bus lanes in a 16-bit configuration.
Note: Although DiskOnChip Millennium Plus 16MB uses 8-bit access to the internal flash, it can be connected to a
32-Bit (Word) Data Access Mode
In a 32-bit bus system that cannot execute byte- or word-aligned accesses, the system address lines SA0 and SA1 are
always zero. Consecutive long-words (32-bit) are differentiated by SA2 toggling. Therefore, in 32-bit systems that
support only 32-bit data access cycles, DiskOnChip A1 is connected to the first system address bit that toggles, i.e.
SA2. DiskOnChip A0 is connected to VSS to configure it for 16-bit operation (see Table 6).
Note: The prefix “S” indicates system host address lines
TrueFFS Driver Modifications
TrueFFS supports a wide range of OSs (see Section 6.1.1). The TrueFFS driver is set to work in 8-bit data access
mode as the default. To support 16-bit/32-bit data access modes and their related memory window allocations,
TrueFFS must be modified. In Windows CE and Windows NT Embedded, these changes can be implemented
through the Registry Entries. In all other cases, some minor customization is required in the driver. Please refer to
the readme of each specific driver for further information.
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16-bit bus. The TrueFFS driver handles all the issues regarding routing data to and from DiskOnChip
Millennium Plus. The Programmable Boot Block is accessed as a true 16- bit device. It responds with the
appropriate data when the CPU issues either an 8-bit or 16-bit read cycle.
When the host BHE# signal asserts DiskOnChip Millennium Plus BHE#, data is valid on D[15:8].
When both A[0] and BHE# are at logic 0, data is valid on D[15:0].
No data is transferred when both BHE# and A0 are logic 1.
16-bit hosts that do not support byte transfers may hardwire the A0 and BHE# inputs to logic 0.
SA13
A12
SA12
A11
BHE#
0
0
1
1
SA11
A10
Inputs
Table 6: Active Data Bus Lanes in 16-bit Configuration
SA10
A9
Figure 20: 32-bit (Word) Data Access Mode
A0
0
1
0
1
SA9
A8
Data Sheet, Rev. 1.7
SA8
A7
D[7:0]
Data Bus Activity
System Host
DiskOnChip
SA7
A6
SA6
A5
D[15:8]
SA5
A4
SA4
A3
DiskOnChip Millennium Plus 16/32/64MByte
Transfer Type
No Operation
Even Byte
SA3
Odd Byte
A2
Word
SA2
A1
SA1
A0
SA0
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