Specifications

Program Memory
3-10
3.4 Program Memory
In addition to storing the user code, the program memory also stores immedi-
ate operands and table information. A maximum of 64K 16-bit words can be
addressed in the program memory for ’240x. This number includes on-chip
DARAM and flash EEPROM/ROM. Whenever an off-chip memory location
needs to be accessed, the appropriate control signals for external access (PS
,
DS, STRB, etc.) are automatically generated.
Figure 3–7 shows the ’LF2407 program memory map.
Figure 3–7. Program Memory Map for ’LF2407
0000h
003Fh
0040h
FDFFh
FE00h
FFFF
0000h–0001h
0002h–0003h
0004h–0005h
0006h–0007h
0008h–0009h
000Ah–000Bh
000Ch–000D
h
000Eh–000Fh
0022h–0023h
0024h–0025h
External
Reset
Interrupt level 1
Interrupt level 2
Interrupt level 3
Interrupt level 4
Interrupt level 5
Interrupt level 6
TRAP
NMI
0010h–0021hSoftware interrupts
Reserved
Reserved
0026h–0027h
7FFFh
8000h
On-chip
FEFF
FF00
DARAM (B0)
(CNF = 1)
(External if CNF = 0)
32K on-chip flash (MP/MC = 0)
External (MP/MC
= 1)
Software interrupts 0028h–003Fh
Reserved
(CNF = 1)
(External if CNF = 0)
User code in
flash memory
Interrupt
vectors
3.4.1 Program Memory Configuration
Two factors determine the configuration of program memory:
- CNF bit. The CNF bit (bit 12) of status register ST1 determines whether
DARAM B0 is in on-chip program space:
J CNF = 0. The 256 words are mapped as external memory.
J CNF = 1. The 256 words of DARAM B0 are configured for program
use. At reset, B0 is mapped to data space (CNF = 0).