SM55161A Datasheet, PDF (15/64 Pages) Austin Semiconductor – 262144 x 16 BIT VRAM MULTIPORT VIDEO RAM

Austin Semiconductor, Inc.
VRAM
SM55161A
Production
block write
The block-write feature allows up to 128 bits of data to be
written simultaneously to one row of the memory array. This
function is implemented as eight columns by eight DQs and
repeated in two halves. In this manner, each of the two 2M-bit
halves can have up to eight consecutive columns written at a
time with up to eight DQs per column (see Figure 9).
Each 2M-bit half has a 8-bit column mask to mask off and
prevent any or all of the eight columns from being written with
data. Nonpersistent write-per-bit or persistent write-per-bit
functions can be applied to the block-write operation to
provide write-masking options. The DQ data is provided by 8
bits from the on-chip color register. Bits 0–7 from the 16-bit
write-mask register, bits 0 –7 from the 16-bit column-mask
register, and bits 0 –7 from the 16-bit color-data register
configure the block write for the first half, while bits 8 - 15 of the
corresponding register control the other half in a similar
fashion (see Figure 10).
FIGURE 9: Block-Write Operation
SMJ55161A
Rev. 1.6 03/05
15
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