MSM514262 datasheet(39/45 Pages) OKI

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MSM514262

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SAM PORT OPERATION

Single Register Mode

High speed serial read or write operation can be reformed through the SAM port independent

of the RAM port operation, except during read/write transfer cycles. The preceding transfer

operation determines the direction of data flow through the SAM port. If the preceding transfer

is a read transfer, the SAM port is in the output mode. If the preceding transfer is write or pseudo

write transfer, the SAM port is in the input mode. The pseudo write transfer only switches the

SAM port from output mode into mode (Data is not transferred from SAM port to RAM port).

Serial data can be read out of the SAM after a read transfer has been performed. The data is

shifted out to the SAM starting at any of the 512 bits locations.

The TAP location corresponds to the column address selected at the falling edge of CAS during

the read or write transfer cycle. The SAM registers are configured as circular data register. The

data is shifted out sequentially starting from the selected TAP location to the most significant

bit (511) and then wraps around to the least significant bit (0).

Split Register Mode

In split register mode, data can be shifted into or out of one half of the SAM while a split read

or split write transfer is being performed on the other half of the SAM.

Conventional (non split) read, write, or pseudo write transfer cycle must precede any split read

or split write transfers. The split read and write transfers will not change the SAM port mode

set by preceding conventional transfer operation. In the split register mode, serial data can be

shifted in or out of the split SAM registers starting from any at the 256 TAP locations, excluding

the last address of each split SAM, data is shifted in or out sequentially starting from the selected

TAP location to the most significant bit (255 or 511) of the first split SAM and, then the SAM

pointer moves to the TAP location selected for the second split SAM to shift data in or out

sequentially starting from this TAP location to the most significant bit (511 or 255) and finally

wraps around to the least significant bit.

255

256

511

TAP

257

TAP

MSM514262 Datasheet(PDF) 39 Page - OKI electronic componets