SM55161A Austin Semiconductor, SM55161A Datasheet - Page 19
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SM55161A
Manufacturer Part Number
SM55161A
Description
262144 x 16 BIT VRAM MULTIPORT VIDEO RAM
Manufacturer
Austin Semiconductor
Datasheet
1.SM55161A.pdf
(64 pages)
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DRAM-to-SAM transfer operation
(512 columns) in the DRAM array is selected to be transferred
to the 512-bit serial-data register. The transfer operation is
invoked by TRG\ being brought low and WE\ being held high
on the falling edge of RAS\. The state of DSF, which is latched
on the falling edge of RAS\, determines whether the full-
register-transfer read operation or the split-register-transfer read
operation is performed (see Table 4).
TABLE 4: SAM Fuction Table
LEGEND:
X = Don’t Care
NOTES:
1. Logic L is selected when either CASL\ or CASU\ are low.
FIGURE 15: Example of Full-Register-Transfer Read Operations
SMJ55161A
Rev. 1.6 03/05
Full-register-transfer Read
Split-register-transfer Read
During the DRAM-to-SAM transfer operation, one row
FUNCTION
Austin Semiconductor, Inc.
CASx\
H
H
1
TRG\
RAS\ FALL
L
L
WE\
H
H
19
full-register-transfer read
selected half of a row in the DRAM into the SAM. TRG\ is
brought low and latched at the falling edge of RAS\. Nine row-
address bits (A0–A8) are also latched at the falling edge of
RAS\ to select one of the 512 rows available for the transfer.
The nine column-address bits (A0– A8) are latched at the first
falling edge of CASx\. Address bits A0–A8 select one of the
SAM’s 512 available tap points from which the serial data is
read out.
early load, real-time load (or midline load), or late load. Each of
these offers the flexibility of controlling the TRG\ trailing edge
in the full-register-transfer read cycle (see Figure 15).
DSF
H
L
A full-register-transfer read operation loads data from a
A full-register-transfer read can be performed in three ways:
CASx\
FALL
DSF
X
X
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
Address
Address
RAS\
Row
Row
ADDRESS
CASX\
Point
Point
Tap
Tap
RAS\
Production
DQ0-DQ15
X
X
SM55161A
VRAM
CASx\
WE\
X
X
CODE
MNE
SRT
RT