8XC196MC, MD, MH USER’S MANUAL

4-2

4.1.3 Program MemoryProgram memory occupies a memory partition beginning at 2080H. (See Table 4-1 for the endingaddress for each device.) This entire parti tion is availa ble for storing e xecutabl e code and dat a.The EA# signal controls access to program memory. Accesses to this address range are directedto internal memory if EA# is held high and to external memory if EA# is held low. For deviceswithout internal nonvolatile memory, the EA# signal must be tied low. EA# is latched at reset.

NOTE

We recommend that you write FFH (the opcode for the RST ins truct ion) to unused program memory locations. This causes a device reset if a program unintentionally begins to execute in unused memory.

Table 4-1. Memory Map

Device and
Hex Address
Range Description Addressing Modes
MC, MD MH
FFFF
6000 FFFF
A000 External device (memory or I/O) connected to the
address/data bus Indirect or indexed
5FFF
2080 9FFF
2080 Program memory (inter na l nonvo la ti le or externa l
memory); see Note 1. Indirect or indexed
207F
2000 207F
2000 Special-purpo se memory (intern al nonvolatile or
external memory ) Indirect or indexed
1FFF
1FE0 1FFF
1FE0 Memory-mapped SFRs Indirect or indexed
1FDF
1F00 1FDF
1F00 Peripheral SF Rs Indirect, indexed, or
windowed direct
1EFF
0200 1EFF
0300 External device (memory or I/O) connected to the
address/data bus (future SFR e xpansion; see Note 2) Indi rect or indexe d
01FF
0100 02FF
0100 Upper regi ster file (gen eral-purpose re gister RAM) Indirect, indexed, or
windowed direct
00FF
0000 00FF
0000 Lower register f ile (general-purpose register RAM,
stack pointer, and CPU SFRs) Direct, indirect, or indexed
NOTES:
1. After a reset, the device fetches its first instruction fro m 2080H.
2. The content or function of the se locations may change in futu re device revisions, in which case a pro-
gram that relies on a location in this range might not fu nctio n pro pe rly.