¡ Semiconductor

MSM518221A

1/16

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.

TheMSM518221AprovideshighspeedFIFO,First-InFirst-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.

¡ Semiconductor

MSM518221A

262,214-Word

¥ 8-Bit Field Memory

E2L0066-18-Z2

This version: Dec. 1998