MITSUBISHI MEMORY CARD

STATIC RAM CARDS

MITSUBISHI

ELECTRIC

2/14

Apr. 1999 Rev. 1.1

5. SUMMARY

MF3XXX-J9CATXX series is the Static RAM cards which has 8/16 bit changeable data-bus width.

The card has a replaceable lithium main battery to maintain data in memory and has an auxiliary battery to

maintain data in memory while the main battery is replaced. When the card is not use or the supply voltage

drops, the main battery will automatically maintain data in memory.

6. FUNCTIONAL DESCRIPTION

The function of the card is determined by the combination of the following five control signals,

REG#, CE1#, CE2#, OE#, WE#; active low signals.

((1))COMMON MEMORY FUNCTION

When REG# signal is high level, the common memory area is selected.

((a))READ MODE

To read, WE# is set high level and CE1# or CE2# is set low level and the memory address is applied at inputs

A0-A21

(4MB). Setting OE# low level executes the reading with output at data-bus. It is available to make the

following functions according to the combination of CE1# and CE2#.

When CE1# is set low level and CE2# is set high level, the card operates as an 8 bit data-bus width card.

The data can be dealt with lower data-bus

(D0-D7).

When both CE1# and CE2# are set low level, the card operates as a 16 bit data-bus width card.

At this mode LSB of address-bus

(A0) is ignored.

In addition odd byte can be accessed through upper data-bus

(D8-D15) when CE1# is set high level and CE2# is

set low level. This mode is useful when handling only odd bytes in the 16 bit data-bus interface system

(A0 is

ignored

).

When both CE1# and CE2# are set high level, the card becomes a standby mode where the card consumes

low power and the data-bus is placed in high impedance state

(above functions of CE1# and CE2# are the same

as in the following modes

).

When both OE# and WE# are set high level, the card becomes a output disable mode and the data-bus is

placed in high impedance state.

((b))WRITE MODE

To write, the memory address is first applied at inputs A0-A21

(4MB) and the data is applied at output pins.

Setting CE1# or CE2# low level, WE# low level and OE# high level executes the writing.

((2))ATTRIBUTE MEMORY FUNCTION

When REG# is set low level, the attribute memory area is selected. MF3XXX-J9CATXX series have no

attribute memory but outputs FFh on the lower data-bus(D0-D7) when the following conditions are applied

(a)setting CE1# low, CE2# high, OE# low, WE# high and A0 low

(b)setting CE1# low, CE2# low, OE# low and WE# high

((3))BATTERY

When the card is used for long periods of time, eventually battery exhaustion occurs. If such a situation is

encountered, replace any exhausted battery with a new one as directed in section 21.2

(page 14).

The replacement battery model number is indicated under section 21

7. WRITE PROTECT MODE

When the write protect switch is switched on, this card goes into a write protect mode that can read but not

write data. In this mode, WP pin becomes “H” level.

At the shipment the write protect switch is switched off (Normal mode : The card can be written ; WP pin

indicates “L” level).