MCM69P817

5

MOTOROLA FAST SRAM

Next Cycle

Address

Used

SE1

SE2

SE3

ADSP

ADSC

ADV

G 3

DQx

Write 2, 4

Deselect

None

1

X

X

X

0

X

X

High–Z

X

Deselect

None

0

X

1

0

X

X

X

High–Z

X

Deselect

None

0

0

X

0

X

X

X

High–Z

X

Deselect

None

X

X

1

1

0

X

X

High–Z

X

Deselect

None

X

0

X

1

0

X

X

High–Z

X

Begin Read

External

0

1

0

0

X

X

X

High–Z

X5

Begin Read

External

0

1

0

1

0

X

X

High–Z

READ5

Continue Read

Next

X

X

X

1

1

0

1

High–Z

READ

Continue Read

Next

X

X

X

1

1

0

0

DQ

READ

Continue Read

Next

1

X

X

X

1

0

1

High–Z

READ

Continue Read

Next

1

X

X

X

1

0

0

DQ

READ

Suspend Read

Current

X

X

X

1

1

1

1

High–Z

READ

Suspend Read

Current

X

X

X

1

1

1

0

DQ

READ

Suspend Read

Current

1

X

X

X

1

1

1

High–Z

READ

Suspend Read

Current

1

X

X

X

1

1

0

DQ

READ

Begin Write

External

0

1

0

1

0

X

X

High–Z

WRITE

Continue Write

Next

X

X

X

1

1

0

X

High–Z

WRITE

Continue Write

Next

1

X

X

X

1

0

X

High–Z

WRITE

Suspend Write

Current

X

X

X

1

1

1

X

High–Z

WRITE

Suspend Write

Current

1

X

X

X

1

1

X

High–Z

WRITE

NOTES:

1. X = don’t care. 1 = logic high. 0 = logic low.

2. Write is defined as either (a) any SBx and SW low or (b) SGW is low.

3. G is an asynchronous signal and is not sampled by the clock K. G drives the bus immediately (tGLQX) following G going low.

4. On write cycles that follow read cycles, G must be negated prior to the start of the write cycle to ensure proper write data setup times. G must

also remain negated at the completion of the write cycle to ensure proper write data hold times.

5. This read assumes the RAM was previously deselected.

1st Address (External)

2nd Address (Internal)

3rd Address (Internal)

4th Address (Internal)

X . . . X00

X . . . X01

X . . . X10

X . . . X11

X . . . X01

X . . . X10

X . . . X11

X . . . X00

X . . . X10

X . . . X11

X . . . X00

X . . . X01

X . . . X11

X . . . X00

X . . . X01

X . . . X10

1st Address (External)

2nd Address (Internal)

3rd Address (Internal)

4th Address (Internal)

X . . . X00

X . . . X01

X . . . X10

X . . . X11

X . . . X01

X . . . X00

X . . . X11

X . . . X10

X . . . X10

X . . . X11

X . . . X00

X . . . X01

X . . . X11

X . . . X10

X . . . X01

X . . . X00

WRITE TRUTH TABLE

Cycle Type

SGW

SW

SBa

SBb

Read

H

H

X

X

Read

H

L

H

H

Write Byte a

H

L

L

H

Write Byte b

H

L

H

L

Write All Bytes

H

L

L

L

Write All Bytes

L

X

X

X