RAM 7.0 Betriebsanweisung PDF herunterladen (Seite 26)

LogiCORE IP Block Memory Generator v6.1

26 www.xilinx.com DS512 March 1, 2011

Product Specification

The operating modes have an effect on the relationship between the A and B ports when the A and B

port addresses have a collision. For detailed information about collision behavior, see Collision

Behavior, page 30. For more information about operating modes, see the block RAM section of the user

guide specific to the device family.

• Write First Mode: In WRITE_FIRST mode, the input data is simultaneously written into memory

and driven on the data output, as shown in Figure 26. This transparent mode offers the flexibility

of using the data output bus during a Write operation on the same port.

Note:

The WRITE_FIRST operation is affected by the optional byte-Write feature in Kintex-7, Virtex-7, Virtex-

6, Virtex-5, Virtex-4, Spartan-6 and Spartan-3A/3A DSP devices. It is also affected by the optional Read-to-

Write aspect ratio feature in Kintex-7, Virtex-7, Virtex-6, Virtex-5 and Virtex-4 devices. For detailed information,

see Write First Mode Considerations, page 30.

• Read First Mode: In READ_FIRST mode, data previously stored at the Write address appears on

the data output, while the input data is being stored in memory. This Read-before-Write behavior

is illustrated in Figure 27.

X-Ref Target - Figure 26

Figure 26: Write First Mode Example

X-Ref Target - Figure 27

Figure 27: Read First Mode Example

WEA

DINA[15:0]

DOUTA[15:0]

CLKA

ADDRA

1111

ENA

cc dd

2222

MEM(aa) 1111 2222 MEM(dd)0000

DISABLED READ

WRITE

MEM(bb)=

1111

WRITE

MEM(cc)=

2222

READ

WEA

DINA[15:0]

DOUTA[15:0]

CLKA

ADDRA

1111

ENA

cc dd

2222

MEM(aa) old MEM(bb) old MEM(cc) MEM(dd)0000

DISABLED READ

WRITE

MEM(bb)=

1111

WRITE

MEM(cc)=

2222

READ

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