VT6516 datasheet(24/73 Pages) ETC

24 / 73 page

VIA Technologies, Inc.

Preliminary VT6516 Datarsheet

-24-

3.1.1 SDRAM interface

All frames received by the VT6516 will be stored into a common frame buffer memory, SDRAM.The

SDRAM contains the packet buffers, each buffer is a 1536 (1.5K) bytes memory block. Each block is

associated to an entry in link table in SRAM. The link entry includes a field (19 bits to support 512 MB) to

point to next link entry. The figure 3-2 is buffer link list structure.

In order to provide the cost effective DRAM buffers, user can connect the 32 bits data SGRAM with

VT6516 switch, there are two external buffer device using two double bank 128Kbits by 32 required. The

following figure shows the minimum configuration of buffer memory and link/address memory. Note that the

SGRAM physical memory hole is to accommodate the forwarding table into the SRAM link list hole.

VT6516

32*32 (128Kb)

SSRAM by one

128K*32*2

(2MB)

SGRAM by two

Memory Hole

(14MB)

Physical Device

(1MB)

Physical Device

(1MB)

Physical Buffer Memory

Allocation (eg, 2MB)

Address table

entries

(Link-List Hole)

Link List

Physical SRAM Memory

Allocation (eg, 128K)

VT6516 Datasheet(PDF) 24 Page - List of Unclassifed Manufacturers