st62t18c STMicroelectronics, st62t18c Datasheet - Page 8

• Manufacturer Part Number: st62t18c
• Description: 8-bit Mcus With A/d Converter, Auto-reload Timer, Uart, Osg, Safe Reset And 20-pin Package
• Manufacturer: STMicroelectronics

ST62T18C/E18C
1.3 MEMORY MAP
1.3.1 Introduction
The MCU operates in three separate memory
spaces: Program space, Data space, and Stack
space. Operation in these three memory spaces is
described in the following paragraphs.
Briefly, Program space contains user program
code in Program memory and user vectors; Data
space contains user data in RAM and in Program
memory, and Stack space accommodates six lev-
els of stack for subroutine and interrupt service
routine nesting.
1.3.2 Program Space
Program Space comprises the instructions to be
executed, the data required for immediate ad-
dressing mode instructions, the reserved factory
test area and the user vectors. Program Space is
addressed via the 12-bit Program Counter register
(PC register).
Program Space is organised in 4K pages. 4 of
them are addressed in the 000h-7FFh locations of
the Program Space by the Program Counter and
by writing the appropriate code in the Program
ROM Page Register (PRPR register). A common
Figure 4. Memory Addressing Diagram
8/82
8
0FF0h
0FFFh
0000h
RESET VECTORS
INTERRUPT &
PROGRAM
MEMORY
PROGRAM SPACE
0-63
(STATIC) 2K page is available all the time for inter-
rupt vectors and common subroutines, independ-
ently of the PRPR register content. This “STATIC”
page is directly addressed in the 0800h-0FFFh by
the MSB of the Program Counter register PC 11.
Note this page can also be addressed in the 000-
7FFh range. It is two different ways of addressing
the same physical memory.
Jump from a dynamic page to another dynamic
page is achieved by jumping back to the static
page, changing contents of PRPR and then jump-
ing to the new dynamic page.
Figure 3. 8Kbytes Program Space Addressing
PC
SPACE
000h
7FFh
800h
FFFh
0C0h
0FFh
000h
03Fh
040h
07Fh
080h
081h
082h
083h
084h
Page 0
Page 1
0000h
Static
Page
MEMORY
DATA READ-ONLY
DATA READ-ONLY
WINDOW SELECT
W REGISTER
X REGISTER
Y REGISTER
V REGISTER
ACCUMULATOR
ROM SPACE
BANK SELECT
RAM / EEPROM
BANKING AREA
Page 1
DATA RAM
Static
Page
MEMORY
RAM
WINDOW
DATA SPACE
Page 2
Page 3
1FFFh
VR01568