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S29AL004D
S29AL004D_00_A1  February 18, 2005
A d v a n c e  I n f o r m a t i o n
If the output is low (Busy), the device is actively erasing or programming. (This 
includes programming in the Erase Suspend mode.) If the output is high (Ready), 
the device is ready to read array data (including during the Erase Suspend 
mode), or is in the standby mode.
Table 6 on page 31
 shows the outputs for RY/BY#. 
Figure 13, on page 37
, 
Figure 
14, on page 38
, 
Figure 17, on page 42
, and 
Figure 18, on page 43
 shows RY/BY# 
for read, reset, program, and erase operations, respectively.
DQ6: Toggle Bit I
Toggle Bit I on DQ6 indicates whether an Embedded Program or Erase algorithm 
is in progress or complete, or whether the device has entered the Erase Suspend 
mode. Toggle Bit I may be read at any address, and is valid after the rising edge 
of the final WE# pulse in the command sequence (prior to the program or erase 
operation), and during the sector erase time-out.
During an Embedded Program or Erase algorithm operation, successive read cy-
cles to any address cause DQ6 to toggle. (The system may use either OE# or CE# 
to control the read cycles.) When the operation is complete, DQ6 stops toggling.
After an erase command sequence is written, if all sectors selected for erasing 
are protected, DQ6 toggles for approximately 100 μs, then returns to reading 
array data. If not all selected sectors are protected, the Embedded Erase algo-
rithm erases the unprotected sectors, and ignores the selected sectors that are 
protected. 
The system can use DQ6 and DQ2 together to determine whether a sector is ac-
tively erasing or is erase-suspended. When the device is actively erasing (that is, 
the Embedded Erase algorithm is in progress), DQ6 toggles. When the device en-
ters the Erase Suspend mode, DQ6 stops toggling. However, the system must 
also use DQ2 to determine which sectors are erasing or erase-suspended. Alter-
natively, the system can use DQ7 (see the subsection on 
 DQ7: Data# Polling on 
page 26
).
If a program address falls within a protected sector, DQ6 toggles for approxi-
mately 1 μs after the program command sequence is written, then returns to 
reading array data.
DQ6 also toggles during the erase-suspend-program mode, and stops toggling 
once the Embedded Program algorithm is complete.
Table 6 on page 31
 shows the outputs for Toggle Bit I on DQ6. 
Figure 6, on page 
30
 shows the toggle bit algorithm. 
Figure 20, on page 44
 shows the toggle bit 
timing diagrams. 
Figure 21, on page 45
 shows the differences between DQ2 and 
DQ6 in graphical form. See also the subsection on 
 DQ2: Toggle Bit II on 
page 28
.
DQ2: Toggle Bit II
The 
Toggle Bit II 
on DQ2, when used with DQ6, indicates whether a particular 
sector is actively erasing (that is, the Embedded Erase algorithm is in progress), 
or whether that sector is erase-suspended. Toggle Bit II is valid after the rising 
edge of the final WE# pulse in the command sequence.
DQ2 toggles when the system reads at addresses within those sectors that are 
selected for erasure. (The system may use either OE# or CE# to control the read 
cycles.) But DQ2 cannot distinguish whether the sector is actively erasing or is 
erase-suspended. DQ6, by comparison, indicates whether the device is actively 
erasing, or is in Erase Suspend, but cannot distinguish which sectors are selected