ST6373 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST6373

8-BIT ROM/OTP/EPROM MCUs FOR DIGITALLY CONTROLLED MULTISYNC/MULTISTANDARD MONITORS

STMicroelectronics 

ST6373

1.3 MEMORY SPACES

The MCU operates in three different memory

spaces: Stack Space, Program Space and Data

Space.

1.3.1 Stack Space

The stack space consists of six 12 bit registers that

are used for stacking subroutine and interrupt re-

turn addresses plus the current program counter

register.

1.3.2 Program Space

The program space is physically implemented in

the ROM and includes all the instructions that are

to be executed, as well as the data required for the

immediate addressing mode instructions, the re-

served test area and user vectors. It is addressed

thanks to the 12-bit Program Counter register (PC

register) and the ST6 Core can directly address up

to 4K bytes of Program Space. Nevertheless, the

Program Space can be extended by the addition

of 2-Kbyte memory banks as it is shown inFigure

2, in which the 16K bytes memory is described.

These banks are addressed by pointing to the

000h-7FFh locations of the Program Space thanks

to the Program Counter, and by writing the appro-

priate code in the Program ROM Page Register

(PRPR) located at address CAh in the Data

Space. Because interrupts and common subrour-

outines should be available all the time only the

Figure 4. Memory Addressing Diagram

lower 2K byte of the 4K program space are bank

switched while the upper 2K byte can be seen as

static space. Table 3 gives the different codes that

allows the selection of the corresponding banks.

Note that, from the memory point of view, the Page

1 and the Static Page represent the same physical

memory: it is only a different way of addressing the

same location.

Figure 3. 16K-Byte Program Space Addressing

Program

counter

space

0000h

1FFFh

0FFFh

Static

Page

Page 1

0800h

07FFh

Page 1

Page 0

Static

Page

Page

2

Page Page

34

Page

5

Page

6

Page

7

0000h

PROGRAM SPACE

DATA SPACE

PROGRAM COUNTER

0000h

STACK LEVEL 1

STACK LEVEL 2

STACK LEVEL 3

STACK LEVEL 4

STACK LEVEL 5

STACK LEVEL 6

ROM

0FF0h

INTE RRUPT &

RESET VECTORS

0FFFh

0-63

000h

RAM / EEPROM

BANKING AREA

03Fh

040h

07Fh

080h

081h

082h

083h

084h

0C0h

0FFh

DATA ROM

WIND OW

X REGISTER

Y REGISTER

V REGISTER

W REGISTER

RAM

DATA ROM

WINDOW SELECT

DATA RAM

BANK SELECT

ACCUMU LATOR

8/64

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