Maxim Integrated MAXQ610 - Manual (Page 16)

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MAXQ610 User’s Guide
2.5.2 Memory Mapping into Code Space
The effective program address can be anywhere in the full 64KB memory space . Program memory from 0000h to
7FFFh is the normal user code segment, followed by the utility ROM . The top of the memory is the logical area for data
memory when accessed as a code segment .
2.5.3 Memory Mapping Rules
When executing program code in a particular memory segment, the same memory segment cannot be simultaneously
accessed as data .
The following is a summary of the memory mapping rules .
• When executing from the normal user code segment:
The lower 32KWords program space (P0 and P1) is always executable as program .
The utility ROM is an extension of the program space if the UPA bit is 0 .
The physical data memory is available for access as a code segment with offset at 0A000h if the UPA bit is 0 .
Load and store operations to data memory are executed normally when addressed to the physical data memory .
The utility ROM can be read as data, starting at 08000h of the data space .
• When executing from the utility ROM (only when UPA bit is 0):
The lower 32KWords program space (P0 and P1) functions as normal program memory .
Data memory is available for access as a code segment at the upper half of the program memory map, immediately
following the utility ROM segment .
Load and store operations to data memory are executed normally when addressed to the physical data memory .
P0 can be accessed as data with offset at 08000h when CDA[1:0] = 00b in byte mode or CDA1 = 0 in word mode .
P1 can be accessed as data with offset at 08000h when CDA[1:0] = 01b in byte mode or at offset 0C000h when
CDA1 = 0 in word mode .
Figure 2-6. MAXQ610 Memory Map and UPA
PHYSICAL DATA
x0000
x8000
x3FF
DATA MEMORY
0 15
LOGICAL SPACE
MAXQ610 MEMORY MAP (DEFAULT, UPA = 0)
xFFFF
PHYSICAL PROGRAM
(P0)
UTILITY ROM
x0000
x8000
xA000
xFFFF
PROGRAM MEMORY
15 0
LOGICAL SPACE
PHYSICAL PROGRAM
(P1)