PM3350-SW datasheet(170/224 Pages) PMC

170 / 224 page

ELAN 8X10

PM3350 ELAN 8 X10

DATA SHEET

PMC-970109

ISSUE 3

8 PORT ETHERNET SWITCH

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND PMC-SIERRA, INC. CUSTOMERS ONLY

168

PROGRAMMER'S MODEL

This section contains information pertinent to RISC firmware designers.

Local Memory Map

The ELAN 8x10 creates and uses data structures stored in an external local memory

that is organized as a contiguous 16MB address space. Memory addresses are 24 bits

in width, and reference 8-bit bytes in little-endian form, i.e. the least-significant byte is

located at the lowest byte offset within a 32-bit word or 16-bit halfword.

General-Purpose Registers

There are sixteen 16-bit general registers,

gr0 through gr15. They are used for all

arithmetic operations, memory load and store operations, and branch condition tests,

and are accessed via CPU instructions.

All general registers are identical; they are all readable and writable by software.

An alternate bank of registers is switched in to replace the current set of general

registers when the REGSW instruction is executed or an exception is taken. The

alternate registers are accessed with the same indices as the normal register set.

Special-Purpose Registers

The special-purpose registers implement memory pointers, hold subroutine return

addresses, contain exception control and status information, support the microcode

instructions, and implement the real-time clock and alarms.

The contents of any special-purpose register may be accessed or modified by the

MOVE and LDI instructions.

The memory pointers (MP0-MP6) are replaced by an alternate bank of registers when

the REGSW instruction is executed or an exception is taken. The alternate registers

are accessed in the same way and by the same instructions as the main register set.

PM3350-SW Datasheet(PDF) 170 Page - PMC-Sierra, Inc