E2L0066-18-Z2
¡ Semiconductor
MSM518221A
¡ Semiconductor
This version: Dec. 1998
MSM518221A
262,214-Word ¥ 8-Bit Field Memory
DESCRIPTION
The OKI MSM518221A is a high performance 2-Mbit, 256K ¥ 8-bit, Field Memory. It is designed
for high-speed serial access applications such as HDTVs, conventional NTSC TVs, VTRs, digital
movies and Multi-media systems. It is a FRAM for wide or low end use as general commodity
TVs and VTRs, exclusively. The MSM518221A is not designed for the other use or high end use
in medical systems, professional graphics systems which require long term picture, and data
storage systems and others. The 2-Mbit capacity fits one field of a conventional NTSC TV screen.
Each of the 8-bit planes has separate serial write and read ports. These employ independent control
clocks to support asynchronous read and write operations. Different clock rates are also supported,
which allow alternate data rates between write and read data streams.
The MSM518221A provides high speed FIFO, First-In First-Out, operation without external refreshing:
it refreshes its DRAM storage cells automatically, so that it appears fully static to the users.
Moreover, fully static type memory cells and decoders for serial access enable the refresh free serial
access operation, so that serial read and/or write control clock can be halted high or low for any
duration as long as the power is on. Internal conflicts of memory access and refreshing operations
are prevented by special arbitration logic.
The MSM518221A's function is simple, and similar to a digital delay device whose delay-bit-length
is easily set by reset timing. The delay length, and the number of read delay clocks between write
and read, is determined by externally controlled write and read reset timings.
Additional SRAM serial registers, or line buffers for the initial access of 256 ¥ 8-bit enable high speed
first-bit-access with no clock delay just after the write or read reset timings.
The MSM518221A is similar in operation and functionality to OKI 1-Mbit Field Memory
MSM514221B. It has a write mask function or input enable function (IE), and read-data skipping
function or output enable function (OE). The differences between write enable (WE) and input
enable (IE), and between read enable (RE) and output enable (OE) are that WE and RE can stop
serial write/read address increments, but IE and OE cannot stop the increment, when write/
read clocking is continuously applied to MSM518221A. The input enable (IE) function allows
the user to write into selected locations of the memory only, leaving the rest of the memory
contents unchanged. This facilitates data processing to display a "picture in picture" on a TV
screen.
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