MSM514262 datasheet(40/45 Pages) OKI

40 / 45 page

¡ Semiconductor

MSM514262

40/45

DATA TRANSFER OPERATION

The MSM514262 features two types of bidirectional data transfer capability between RAM and

SAM, as shown in Figure 1 below.

Conventional (non split) transfer : 512 words by 4 bits of data can be loaded from RAM

to SAM (Read transfer) or from SAM to RAM (Write transfer).

Split transfer : 256 words by 4 bits of data can be loaded from the lower/upper half of the

RAM to the lower/upper half of the SAM (Split read transfer) or from the lower/upper half

of SAM to the lower/upper half of RAM (Split write transfer).

The conventional transfer and split transfer modes are controlled by the DSF input signal.

512 ¥ 512 ¥ 4

Memory

Array

512 ¥ 4

512 ¥ 256 ¥ 4

Memory

Array

256 ¥ 4

512 ¥ 256 ¥ 4

Memory

Array

256 ¥ 4

1) Conventional Transfer

2) Split Transfer

Figure 1.

The MSM514262 supports five types of transfer operation : Read transfer , Split read transfer,

Write transfer, Pseudo write transfer and Split write transfer as shown in truth table. Data

transfer are invoked by holding the DT/OE signal “low” at the falling edge of RAS. The type

of transfer operation is determined by the state of CAS, WB/WE, SE and DSF latched at the

falling edge of RAS. During conventional transfer operations, the SAM port is switched from

input to output mode (Read transfer) or output to input mode (Write/Pseudo write transfer)

Whereas it remains unchanged during split transfer operation (Split read transfer or Split write

transfer).

MSM514262 Datasheet(PDF) 40 Page - OKI electronic componets