
Device Operations (continued) 
  A45L9332A Series 
PRELIMINARY 
(October, 2001, Version 0.1) 
17 
AMIC Technology, Inc.
Write Per Bit 
Write per bit (i.e. I/O mask mode) for SGRAM is a function 
that selectively masks bits of data being written to the 
devices. The mask is stored in an internal register and 
applied to each bit of data written when enabled. Bank 
active command with DSF = High enabled write per bit 
operations is stored in the mask register accessed by 
SWCBR (Special Mode Register Set Command). When a 
mask bit = 1, the associated data bit is written when a write 
command is executed and write per bit has been enabled 
for the bank being written. When a mask bit = 0, the 
associated data bit is unaltered when a write command is 
executed and the write per bit has been enabled for the 
bank being written. No additional timing conditions are 
required for write per bit operations. Write per bit writes can 
be either single write, burst writes or block writes. DQM 
masking is the same for write per bit and non-WPB write. 
Block Write 
Block write is a feature allowing the simultaneous writing of 
consecutive 8 columns of data within a RAM device during 
a single access cycle. During block write the data to be 
written comes from an internal “color” register and DQ I/O 
pins are used for independent column selection. The block 
of column to be written is aligned on 8 column boundaries 
and is defined by the column address with the 3 LSB’s 
ignored. Write command with DSF = 1enables block write 
for the associated bank. A write command with DSF = 0 
enables normal write for the associated bank. The block 
width is 8 column where column = “n” bits for by “n” part. 
The color register is the same width as the data port of the 
chip. It is written via a SWCBR where data present on the 
DQ pin is to be coupled into the internal color register. The 
color register provides the data masked by the DQ column 
select, WPB mask (If enabled), and DQM byte mask. 
Column data masking (Pixel masking) is provided on an 
individual column basis for each byte of data. The column 
mask is driven on the DQ pins during a block write 
command. The DQ column mask function is segmented on 
a per bit basis (i.e. DQ[0:7] provides the column mask for 
data bits[0:7], DQ[8:15] provides the column mask for data 
bits[8:15], DQ0 masks column[0] for data bits[0:7], DQ9 
masks column [1] for data its [8:15], etc). Block writes are 
always non-burst, independent of the burst length that has 
been programmed into the mode register. Back to back 
block writes are allowed provided that the specified block 
write cycle time (t
BWC
) is satisfied. If write per bit was 
enabled by the bank active command with DSF = 1, then 
write per bit masking of the color register data is enabled.  
If write per bit was disabled by a bank active command with 
DSF = 0, the write per bit masking of the color register data 
is disabled. DQM masking provides independent data byte 
masking during block write exactly the same as it does 
during normal write operations, except that the control is 
extended to the consecutive 8 columns of the block write. 
Timing Diagram to Illustrate t
BWC 
High
1 CLK BW
1
0
2
Clock
CKE
CS
RAS
CAS
WE
DSF