4250 查看數據表（PDF） - MITSUBISHI ELECTRIC

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4250

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

MITSUBISHI ELECTRIC  

MITSUBISHI MICROCOMPUTERS

4250 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

PROGRAM MEMORY (ROM)

The program memory is a mask ROM. 1 word of ROM is

composed of 9 bits. ROM is separated every 128 words by the

unit of page (addresses 0 to 127). Table 1 shows the ROM size

and pages. Figure 10 shows the ROM map of M34250M2.

Table 1 ROM size and pages

Product

ROM size (! 9 bits)

M34250M2

M34250E2

2048 words

Pages

16 (0 to 15)

000016

007F16

008016

00FF16

010016

017F16

018016

8 7 6 5 4 3 2 10

Page 0

Interrupt address page

Subroutine special page

Page 1

Page 2

Page 3

A part of page 1 (addresses 008016 to 00FF16) is reserved for

interrupt addresses (Figure 11). When an interrupt occurs, the

address (interrupt address) corresponding to each interrupt is

set in the program counter, and the instruction at the interrupt

address is executed. When using an interrupt service routine,

write the instruction generating the branch to that routine at an

interrupt address.

Page 2 (addresses 010016 to 017F16) is the special page for

subroutine calls. Subroutines written in this page can be called

from any page with the 1-word instruction (BM). Subroutines

extending from page 2 to another page can also be called with

the BM instruction when it starts on page 2.

ROM pattern (bits 7 to 0) of all addresses can be used as data

areas with the TABP p instruction.

DATA MEMORY (RAM)

1 word of RAM is composed of 4 bits, but 1-bit manipulation

(with the SB j, RB j, and SZB j instructions) is enabled for the

entire memory area. A RAM address is specified by a data

pointer. The data pointer consists of registers X and Y. Set a

value to the data pointer certainly when executing an instruction

to access RAM.

Table 2 shows the RAM size. Figure 12 shows the RAM map.

Table 2 RAM size

Product

M34250M2

M34250E2

RAM size

64 words ! 4 bits (256 bits)

07FF16

Fig. 10 ROM map of M34250M2

Page 15

8 7 6 5 4 3 2 10

008016 External interrupt address

008216 Timer 1 interrupt address

00FF16

Fig. 11 Page 1 (addresses 008016 to 00FF16) structure

RAM 64 words ! 4 bits (256 bits)

Register X 0 1 2 3

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

64 words

Fig. 12 RAM map

MITSUBISHI

14

ELECTRIC

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