HTG13J0 データシートの表示（PDF） - Holtek Semiconductor

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HTG13J0

4-Bit Microcontroller

Holtek Semiconductor 

HT13J0

Functional Description

Program counter - PC

The bit 13 of program memory is controlled by

PA3 which can change the address of the pro-

gram. There are two banks of the program

memory, which are selected by PA3, every bank

is 4KB ROM. The instruction "UT PA,A" is used

to change the value of PA3. Then, low or high

4K ROM is selected accordingly. All instruc-

tions are not effective on crossing bank, unless

the value of PA3 is changed in advance.

The 12-bit program counter (PC) controls the

sequence in which the instructions stored in

program ROM are executed and its contents

specify a maximum of 4096 addresses.

After accessing a memory word to fetch an in-

struction code, the contents of the program

counter are incremented by 1 or 2, then the pro-

gram counter will point to the memory word

containing the next instruction code.

When executing the jump instruction (JMP,

JNZ, JC,JTMR...), subroutine call, internal in-

terrupt, external interrupt or return from sub-

routine, the PC manipulates the program

transfer by loading the address corresponding

to each instruction.

Mode

Program Counter

PA3 PC11 PC10 PC9 PC8 PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0

Initial

reset

10

0

00 0 0 00 0

0

0

0

Internal

interrupt

PA3 0

0

00 0 0 00 0

1

0

0

External

interrupt

PA3 0

0

00 0 0 00 1

0

0

0

Jump, call

instruction

PA3 PC11 PC10 PC9 PC8 PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0

Conditional

branch

PA3

@

PC10 PC9 PC8 PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0

Return from

subroutine

PA3

S11

S10

S9

S8

S7

S6

S5

S4

S3

S2

S1

S0

Program counter

Notes: PC11~PC0: Instruction code bits

S11~S0: Stack register bits

@: PC11 keeps the current value

PA3: Bank value bits

8

May 19, 1999

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