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5.1 Overview
The ROM module provides 256 Kbytes of general-purpose code and data storage.
5.2 Functional Description
The 256-Kbyte ROM module supports byte, halfword, and word read accesses with a
32-bit data interface to the CPU. Only the requested bytes are guaranteed to be valid
on accesses. Write cycles that are attempted to the ROM address space are termi-
nated with a TEA response to the CPU.
Address
00000000
to
0003FFFF
00040000
to
000FFFFF
00100000
to
0FFFFFFF
The ROM module base address is located at address 0x0000 0000 when the module
is enabled. Echoing of the ROM block occurs throughout the region 0x0004 0000 –
0x000F FFFF; no attempt is made to detect this condition. Accesses in the range of
0x0010 0000 – 0x0FFF FFFF result in TEA termination to the CPU.
Software designers should be aware that the echoing characteristics of this imple-
mentation may change for future versions of the M•CORE family.
External control is provided to disable the on-chip ROM for system debugging pur-
poses via a control input to the chip. When asserted, the MOD input signal causes
the on-chip ROM to be disabled for the initial program counter fetch out of reset, and
the chip select module to dedicate the CS0 output for an external boot ROM. Refer to
SECTION 4 SIGNAL DESCRIPTIONS and SECTION 7 EXTERNAL INTERFACE
MODULE for details of the interaction of the MOD input signal with the CS0 signal.
MMC2001
REFERENCE MANUAL
All manuals and user guides at all-guides.com
Freescale Semiconductor, Inc.
SECTION 5
ROM MODULE
Table 5-1 ROM Module Address Map
Use
ROM Array
00000001 to 00000003 are used as off-chip boot
vectors when the MOD signal is asserted
ROM echoes on 256-Kbyte boundaries
Not Used (Access causes transfer error)
ROM MODULE
For More Information On This Product,
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Access
Supervisor,
Selective User
Supervisor,
Selective User
Not Applicable
MOTOROLA
5-1
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