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SMJ55166GB

262144 BY 16-BIT MULTIPORT VIDEO RAM

Austin Semiconductor 

functional operation description

SMJ55166

262144 BY 16-BIT

MULTIPORT VIDEO RAM

SGMS057C – APRIL 1995 – REVISED JUNE 1997

Table 3. DRAM Function Table

FUNCTION

RAS FALL

CAS

FALL

ADDRESS

CAS TRG WEx‡ DSF DSF RAS CAS§

DQ0 – DQ15†

RAS

WEL

WEU

CAS

MNE

CODE

Reserved (do not use)

L

L

L

L

X

X

X

X

X

—

CBR refresh (no reset) and stop-point

set (CBRS)¶

L

X

L

H

X

Stop

Point #

X

X

X

CBRS

CBR refresh (option reset)||

CBR refresh (no reset)k

L

X

H

L

X

X

X

X

X

CBR

L

X

H

H

X

X

X

X

X

CBRN

DRAM write

(nonpersistent write-per-bit)

H

H

L

L

L

Row Column Write

Address Address Mask

Valid

Data

RWM

DRAM block write

(nonpersistent write-per-bit)

H

H

L

L

H

Row

Address

Block

Address

A2 – A8

Write

Mask

Column

Mask

BWM

DRAM write

(persistent write-per-bit)

H

H

L

L

L

Row Column

Address Address

X

Valid

Data

RWM

DRAM block write

(persistent write-per-bit)

H

H

L

L

H

Row

Address

Block

Address

A2 – A8

X

Column

Mask

BWM

DRAM write (nonmasked)

H

H

H

L

L

Row Column

Address Address

X

Valid

Data

RW

DRAM block write (nonmasked)

H

H

H

L

H

Row

Address

Block

Address

A2 – A8

X

Column

Mask

BW

Load write-mask register h

H

H

H

H

L

Refresh

Address

X

X

Write

Mask

LMR

Load color register

H

H

H

H

H

Refresh

Address

X

X

Color

Data

LCR

Legend:

Col Mask = H: Write to address/column enabled

Write Mask = H: Write to I/O enabled

X

= Don’t care

† DQ0 – DQ15 are latched on either the first falling edge of WEx or the falling edge of CAS, whichever occurs later.

‡ Logic L is selected when either or both WEL and WEU are low.

§ The column address and block address are latched on the first falling edge of CAS.

¶ CBRS cycle should be performed immediately after the power-up initialization cycle.

# A0 – A3, A8: don’t care; A4 – A7 : stop-point code

|| CBR refresh (option reset) mode ends persistent write-per-bit mode and stop-point mode.

kCBR refresh (no reset) mode does not end persistent write-per-bit mode or stop-point mode.

hLoad-write-mask-register cycle sets the persistent write-per-bit mode. The persistent write-per-bit mode is reset only by the CBR (option reset)

cycle.

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