MD4331-d1G-MECH M-Systems Inc., MD4331-d1G-MECH Datasheet - Page 55

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

8.6
Description:
Address (hex): 1006
Type:
Reset Value:
52
Bit No.
7-0
Bus Lock Register
D[7:0]: CPU Control value
This register provides a mechanism for a CPU to request and hold sole access
rights to Mobile DiskOnChip G3 in multiprocessor applications.
The following algorithm must be implemented to ensure that only one CPU at a
time accesses Mobile DiskOnChip G3:
1.
2.
3.
4.
Read/Write
0
Before beginning an indivisible operation sequence (e.g. reading/writing a
sector to the DiskOnChip), the value of this register is read. If it is non-zero,
then it must continue to be polled until it becomes zero.
Once the value read is zero, a non-zero value unique to each CPU is written
to this register to indicate to other CPUs that the device is in use.
The value written must then be confirmed. If the register returns the same
value that was written, then the CPU is assured of sole access rights to
Mobile DiskOnChip G3. If it is not the same value, then another CPU has
claimed access rights to the device and the process must be repeated from
step 1.
Upon completion of the indivisible operation sequence, this register must be
set to 00H to release the lock and permit other CPUs to access the device.
Data Sheet, Rev. 1.0
Description
Mobile DiskOnChip G3
91-SR-011-05-8L