¡ Semiconductor

MSM6587

11/13

FUNCTIONAL DESCRIPTION

Serial Address Input (SAD)

Pin for inputting the start address for read/write. Address data can be input in units of 1024 words.

The 1,024 address data can be input as 10-bit (A0-A9) serial from the SAD pin. (A0-A8 has enable

address, A9 keeps "L".)

Serial Address Strobe (SAS)

Pin for the clock used to store the serial address data into the internal register.

Address Transfer Strobe (TAS)

Input pin for setting the serial address data stored in the address register to the internal address

counter.

When the TAS falls, and the Y address is set to address 0 in the increment mode or to address

1023 in the decrement mode.

Read/Write Clock (RWCK)

Input pin for the data register information read/write clock.

Internal operation starts at the falling edge of RWCK. The information in the data register is output

to the DOUT pin in the read mode, and the information at the DIN pin is written into the data register

in the write mode. The internal address counter is automatically incremented or decremented also

when RWCK falls.

Write Enable (WE)

Input pin for selecting the read mode, write mode or read modify write mode.

The read mode is set when WE is "H", and the write mode is set when WE is "L". When WE falls from

"H" to "L" while RWCK is active, the read modify write mode is set.

Data Input (DIN)

Input pin for write data.

The information at the data input pin is stored at the falling edge of RWCK in the write mode, and

at the falling edge of WE in the read modify write mode.

Data Output (DOUT)

The data output pin is always kept in the high impedance state when RWCK or CS is kept at "H".

When "H" or "L" information is read in the read operation, the output pin is set to "H" or "L" and holds

thereadinformationuntilRWCK isagainsetto"H".Intheearlywritemodetheoutputpinmaintains

the high impedance state, so I/O common operation by connecting DIN and DOUT is possible.

Address Up/Down Select (AU/D)

Input pin for selecting the direction of automatic address updating.

When the TAS signal is input with the AU/D pin set to "H", the internal address counters are set to

the externally set address for X and to address 0 for Y. Then the address is incremented by 1 every

time RWCK is input.

When the TAS signal is input with the AU/D pin set to "L", the internal address counters are set to

the externally set address in the same way for X but set to address 1023 for Y. Then the address is

decremented by 1 every time RWCK is input. In either case, the X address is automatically

incremented or decremented by 1 when read/write operation for 1024 words ends. The AU/D pin

are satisfied.