
A49LF040 
PRELIMINARY (March, 2006, Version 0.1) 
9 
AMIC Technology, Corp.
REGISTERS 
There are two types of registers available on the A49LF040A, 
the General Purpose Inputs Register, and the JEDEC ID 
Registers. These registers appear at their respective address 
location in the 4 GByte system memory map. Unused 
register locations will read as 00H. Any attempt to read or 
write any register during an internal Write operation will be 
ignored. Refer to Table 7 for the LPC register memory map. 
General Purpose Inputs Register 
The GPI_REG (General Purpose Inputs Register) passes the 
state of GPI[4:0] pins at power-up on the A49LF040A. It is 
recommended that the GPI[4:0] pins be in the desired state 
before LFRAME  is brought low for the beginning of the next 
bus cycle, and remain in that state until the end of the cycle. 
There is no default value since this is a pass-through register. 
See Table 8
for the GPI_REG bits and function, and Table 7 
for memory address locations for its respective device 
strapping. 
Table 8: General Purpose Inputs Register 
Bit  
Name 
Pin Number 
Bit 
Function 
32-PLCC 32-TSOP
- 
7:5 
- 
Reserved 
- 
4 
GPI[4] 
GPI_REG Bit 4 
30 
6 
3 
GPI[3] 
GPI_REG Bit 3 
3 
11 
2 
GPI[2] 
GPI_REG Bit 2 
4 
12 
1 
GPI[1] 
GPI_REG Bit 1 
5 
13 
0 
GPI[0] 
GPI_REG Bit 0 
6 
14 
Block Locking Registers 
A49LF040A provides software controlled lock protection 
through a set of Block Locking registers. The Block Locking 
Registers are read/write registers and it is accessible through 
standard addressable memory locations specified in Table 7. 
See Table 9 for Bit definition of the Block Lock Register.  
Write-Lock. 
The Write-Lock Bit determines whether the 
contents of the Block can be modified (using the Program or 
Erase Command). When the Write-Lock Bit is set to ‘1’, the 
block is write protected; any operations that attempt to 
change the data in the block will fail and the Status Register 
will report the error. When the Write-Lock Bit is reset to ‘0’, 
the block is not write protected through the Locking Register 
and may be modified unless write protected through some 
other means. If Top Block Lock, 
TBL
 , is Low, V
IL
, then the 
Top Block (Block 7) is write protected and cannot be 
modified. Similarly, if Write Protect, 
WP
 , is Low, V
IL
, then 
the Main Blocks (Blocks 0 to 6) are write protected and 
cannot be modified. After power-up or reset the Write-Lock 
Bit is always set to ‘1’ (write protected).
Read-Lock. 
The Read-Lock bit determines whether the 
contents of the Block can be read (from Read mode). When 
the Read-Lock Bit is set to ‘1’, the block is read protected; 
any operation that attempts to read the contents of the block 
will read 00h instead. When the Read-Lock Bit is reset to ‘0’, 
read operations in the Block return the data programmed into 
the block as expected. After power-up or reset the Read-
Lock Bit is always reset to ‘0’ (not read protected). 
Lock-Down. 
The Lock-Down Bit provides a mechanism for 
protecting software data from simple hacking and malicious 
attack. When the Lock-Down Bit is set to ‘1’, further 
modification to the Write-Lock, Read-Lock and Lock-Down 
Bits cannot be performed. A reset or power-up is required 
before changes to these bits can be made. When the Lock-
Down Bit is reset to ‘0’, the Write-Lock, Read-Lock and Lock-
Down Bits can be changed. 
JEDEC ID Registers 
The JEDEC ID registers identify the device as A49LF040A 
and manufacturer as AMIC in LPC mode. See Table 7 for 
memory address locations for its respective JEDEC ID 
location. 
Table 4: Address Bit Definition 
A
31
:A
23
A
23
A
22
A
21
:A
19
A
18
:A
0
1111 1111b 
ID[3] 
1 = Memory access 
0 = Register access 
ID[2:0] 
Device memory address