To verify programming of the protection circuitry, the programming equipment must force VID on address pin A9
with CE and OE at VIL and WE at VIH. Scanning the sector addresses (A16, A17 and A18) while (A6, A1, A0) = (0,
1, 0) will produce a logical โ1โ code at device output DQ0 for a protected sector. Otherwise the device will read
00H for unprotected sector. In this mode, the lower order addresses, except for A0, A1 and A6 are DONโT CARES.
Address locations with A1 = VIL are reserved for Autoselect manufacturer and device codes.
It is also possible to determine if a sector is protected in the system by writing an Autoselect command. Performing
a read operation at the address location XX02H, where the higher order addresses (A16, A17 and A18) are the
sector address will produce a logical โ1โ at DQ0 for a protected sector. See Table 3 for Autoselect codes.
Table 5 MBM29F040C Command Definitions
First Bus Second Bus
Write Cycle Write Cycle
Addr Data Addr Data
1 XXXH F0H โ โ โ โ โ โ โ โ โ โ
4 555H AAH 2AAH 55H 555H F0H RA RD โ โ โ โ
3 555H AAH 2AAH 55H 555H 90H โ โ โ โ โ โ
4 555H AAH 2AAH 55H 555H A0H PA PD โ โ โ โ
6 555H AAH 2AAH 55H 555H 80H 555H AAH 2AAH 55H 555H 10H
6 555H AAH 2AAH 55H 555H 80H 555H AAH 2AAH 55H SA 30H
Sector Erase Suspend Erase can be suspended during sector erase with Addr (โHโ or โLโ). Data (B0H)
Sector Erase Resume Erase can be resumed after suspend with Addr (โHโ or โLโ). Data (30H)
Notes: 1. Address bits A11 to A18 = X = โHโ or โLโ for all address commands except for Program Address (PA) and
Sector Address (SA).
2. Bus operations are defined in Table 2.
3. RA = Address of the memory location to be read.
PA = Address of the memory location to be programmed. Addresses are latched on the falling edge of the
SA = Address of the sector to be erased. The combination of A18, A17, and A16 will uniquely select any
4. RD = Data read from location RA during read operation.
PD = Data to be programmed at location PA. Data is latched on the falling edge of WE.
*: Either of the two reset commands will reset the device.
Device operations are selected by writing specific address and data sequences into the command register.
Writing incorrect address and data values or writing them in the improper sequence will reset the device to read
mode. Table 5 defines the valid register command sequences. Note that the Erase Suspend (B0H) and Erase
Resume (30H) commands are valid only while the Sector Erase operation is in progress. Moreover, both Read/
Reset Commands are functionally equivalent, resetting the device to the read mode.