Specifications

ST72104Gx, ST72215Gx, ST72216Gx, ST72254Gx
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3 REGISTER & MEMORY MAP
As shown in the Figure 4, the MCU is capable of
addressing 64K bytes of memories and I/O regis-
ters.
The available memory locations consist of 128
bytes of register location, 256 bytes of RAM and
up to 8Kbytes of user program memory. The RAM
space includes up to 128 bytes for the stack from
0100h to 017Fh.
The highest address bytes contain the user reset
and interrupt vectors.
IMPORTANT: Memory locations marked as “Re-
served” must never be accessed. Accessing a re-
served area can have unpredictable effects on the
device.
Figure 4. Memory Map
0000h
Program Memory
(4K, 8 KBytes)
Interrupt & Reset Vectors
HW Registers
DFFFh
0080h
007Fh
(see Table 2)
E000h
FFDFh
FFE0h
FFFFh
(see Table 5 on page 26)
0180h
Reserved
017Fh
Short Addressing RAM
0100h
017Fh
0080h
00FFh
256 Bytes RAM
4 KBytes
F000h
E000h
8 KBytes
FFFFh
Zero page
(128 Bytes)
Stack or
16-bit Addressing RAM
(128 Bytes)