MC80F0204 Datasheet, PDF(25/126 Page) List of Unclassifed Manufacturers

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MC80F0204 Datasheet, PDF (25/126 Pages) List of Unclassifed Manufacturers – 8-BIT SINGLE-CHIP MICROCONTROLLERS

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Preliminary

MC80F0104/0204

8.2 Program Memory

A 16-bit program counter is capable of addressing up to

64K bytes, but this device has 4K bytes program memory

space only physically implemented. Accessing a location

above FFFFH will cause a wrap-around to 0000H.

Figure 8-5 , shows a map of Program Memory. After reset,

the CPU begins execution from reset vector which is stored

in address FFFEH and FFFFH as shown in Figure 8-6 .

As shown in Figure 8-5 , each area is assigned a fixed lo-

cation in Program Memory. Program Memory area con-

tains the user program

F000H

Example: Usage of TCALL

LDA

TCALL 0FH

;

;TABLE CALL ROUTINE

;

FUNC_A: LDA LRG0

RET

;

FUNC_B: LDA LRG1 2

RET

;

;TABLE CALL ADD. AREA

;

ORG 0FFC0H

DW FUNC_A

DW FUNC_B

;1BYTE INSTRUCTION

;INSTEAD OF 3 BYTES

;NORMAL CALL

;TCALL ADDRESS AREA

FEFFH

FF00H

FFC0H

FFDFH

FFE0H

FFFFH

TCALL area

Interrupt

Vector Area

Figure 8-5 Program Memory Map

Page Call (PCALL) area contains subroutine program to

reduce program byte length by using 2 bytes PCALL in-

stead of 3 bytes CALL instruction. If it is frequently called,

it is more useful to save program byte length.

Table Call (TCALL) causes the CPU to jump to each

TCALL address, where it commences the execution of the

service routine. The Table Call service area spaces 2-byte

for every TCALL: 0FFC0H for TCALL15, 0FFC2H for

TCALL14, etc., as shown in Figure 8-7 .

The interrupt causes the CPU to jump to specific location,

where it commences the execution of the service routine.

The External interrupt 0, for example, is assigned to loca-

tion 0FFFCH. The interrupt service locations spaces 2-byte

interval: 0FFFAH and 0FFFBH for External Interrupt 1,

0FFFCH and 0FFFDH for External Interrupt 0, etc.

Any area from 0FF00H to 0FFFFH, if it is not going to be

used, its service location is available as general purpose

Program Memory.

Address

0FFE0H

Vector Area Memory

Basic Interval Timer

Watchdog Timer Interrupt

A/D Converter

Timer/Counter 3 Interrupt

Timer/Counter 2 Interrupt

Timer/Counter 1 Interrupt

Timer/Counter 0 Interrupt

Serial Input/Output (SIO)

UART Tx interrupt

UART Rx interrupt

External Interrupt 3

External Interrupt 2

External Interrupt 1

External Interrupt 0

RESET

Figure 8-6 Interrupt Vector Area

Mar. 2005 Ver 0.2

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