EB632 datasheet(5/112 Pages) FREESCALE

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SIU

Functional Differences Between MSC8101 (Mask 2K42A) and MSC8103 (Mask 2K87M), Rev. 2

Freescale Semiconductor

3.1.2 2K87M Mask Set IMMR Values

IMMR identifies a specific device as well as the base address for the internal memory map. Software can deduce

availability and location of any on-chip system resources from the values in IMMR. PARTNUM and MASKNUM

are mask programmed and cannot be changed for any particular device.

3.2

Internal Memory Map Mirror Register (IMMMR)

The 2K87M mask set adds a new Internal Memory Map Mirror Register (IMMMR) which has a fixed address

controlled by the QBus Bank 1 (0x00F8FFC0) and the same register fields as the IMMR. It reflects the contents of

the IMMR. If the ISB in the IMMR is modified, the base address of all SIU and CPM registers, including the

IMMR, changes to the new value selected by the ISB. In such a case, the device or external masters may not be able

to access the registers. Since the IMMMR does not reside in the same base memory area, it is always available at its

fixed address. You can read the current ISB value from the IMMMR and determine the current internal base

address from that value.

IMMR

Internal Memory Map Register

0x101A8

Bit

ISB

—

Type

R/W

Reset

Depends on reset configuration sequence.

Bit

1617

192021

232425

272829

PARTNUM

MASKNUM

Type

Reset

—

Table 3. IMMR Bit Descriptions

Bits

Description

Settings

ISB

0–14

Internal Space Base

Defines the base address of the internal memory space. The value of ISB is configured at

reset to one of seven addresses; the software can then change it to any value. The default

address is based on the ISB bits in the Hard Reset Configuration Word. The default is zero,

which maps to address 0xF0000000.

ISB defines the 15 msbs of the memory map register base address. IMMR itself is mapped

into the internal memory space region. As soon as the ISB is written with a new base

address, the IMMR base address is relocated according to the ISB. ISB enables the

configuration of multiple-MSC8103 systems.

Implementation-dependent

—

Reserved. Write to zero for future compatibility.

PARTNUM

16–23

Part Number

This field is mask-programmed with a code corresponding to the part number of the part on

which the SIU is located. It helps factory test and user code that is sensitive to part

changes. This field changes when the part number changes. For example, it would change

if any new module is added or if the size of any memory module changes. It does not

change if the part is changed to fix a bug in an existing module.

The MSC8103 has an ID of

0x50.

MASKNUM

24–31

Mask Number

This field is mask-programmed with a code corresponding to the mask number of the part

on which the SIU is located. It helps factory test and user code that is sensitive to part

changes. It is programmed in a commonly changed layer and should be changed for all

mask set changes.

The MSC8103 mask set

2K87M has an ID of 0x12.

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