MSM518221 Datasheet, PDF (1/16 Pages) OKI electronic componets – 262,214-Word x 8-Bit Field Memory

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MSM518221
262,214-Word ¥ 8-Bit Field Memory
This version_M: _SJa_Mn.₅1₁9₈9₂8₂₁
Previous version: Dec. 1996
DESCRIPTION
The OKI MSM518221 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. 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 MSM518221 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 MSM518221'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 MSM518221 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 MSM518221. 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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