R

Hardware Schematic Diagram

Data[7:0]

Addr[10:0]

RAMB16_S9

2047

1280

1279

1024

1023

256

255

0

F0 - FF

E0 - EF

D0 - DF

C0 - CF

B0 - BF

A0 - AF

Not Used

Not Used

70 - 7F

60 - 6F

50 - 5F

40 - 4F

30 - 3F

20 - 2F

10 - 1F

Not Used

The RAM array is divided in pages of eight bytes by 16, forming an array of 128 bytes. This array represents one column of standard ASCII table. A character is stored as:

N-x

N

 

 

 

 

 

 

 

 

 

Shift

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N-1

 

 

 

 

 

 

 

 

 

Addr

 

 

 

 

 

 

 

 

 

Direction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

0 1 2 3 4 5 6 7 Data

UG199_C_10_050106

Figure C-10:Block RAM Organization

When presenting byte value 30 hex, character 0 must be displayed. Shifting the value 00110000b (30h) up three positions gives the value 180h or 348d.

Because each character uses eight byte locations, character 0 in the character set starts from memory location 348 decimal.

For example, character X has byte value 58h or 01011000b. Shifting this value three positions gives the value 2C0h or 704d.

Virtex-5 FPGA ML561 User Guide

www.xilinx.com

137

UG199 (v1.2) April 19, 2008

Page 137
Image 137
Xilinx ML561 manual Figure C-10Block RAM Organization