MFM8126S-70/90/12
ISSUE4.2:November1998
Sector Protection
The MFM8126 features hardware sector protection. This feature will disable both program and erase operations
in any number of sectors (0 through 7). The sector protect feature is enabled using programming equipment at
the users site. The device is shipped with all sectors unprotected.
To activate this mode, the programming equipment must force VID on address pin A9 and control pin OE. The
sector adresses (A16, A15 and A14) should be set to the sector to be protected. Programming of the protection
circuitry begins on the falling edge of the WE pulse and is terminated with the rising edge of the same. Sector
addresses must be held constant during the WE pulse. (See Sector Address Table).To verify programming of the
protection equipment circuitry, the programming equipment must force VID on address pin A9 with CS and OE at
VIL and WE at VIH. Reading the device at a particular sector address (A16, A15 and A14) will produce 01H at data
outputs (D0-D7) for a protected sector. Otherwise the device will read 00H for unprotected sector. In this mode,
the lower order addresses, except for A0 and A1, are don't care. Address location 02H is reserved to verify sector
protection of the device. Address pin A1 must be held at VIH and A0 at VIL. Address location 00H aand 01H are
reserved for autoselect codes. If a verify of the sector protection circuitry were done at these addresses, the
devicewouldoutputthemanufactureranddevicecodesrespectively.
It is also possible to determine if a sector is protected in the system by writing the autoselect command.
Performing a read operation at particular sector addresses (A16, A15 and A14) and with A1=VIH and A0=VIL (other
addresses are a don't care) will produce 01H data if those sectors are protected. Otherwise the device will read
00H for an unprotected sector. (See Sector Protect/Unprotect Algorithms for more details.)
Sector Adresses Table.
A16
A15
A14
Address Range
00000H-3FFFH
04000H-07FFFH
SA0
SA1
SA2
0
0
0
0
0
0
1
1
0
08000H-0BFFFH
SA3
SA4
0
1
1
0
1
0
0C000H-0FFFFH
10000H-13FFFH
SA5
SA6
SA7
1
1
1
0
1
1
1
0
1
14000H-17FFFH
18000H-1BFFFH
1C000H-1FFFFH
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