455A datasheet(21/148 Pages) RENESAS

21 / 148 page

Rev.1.01

Feb 15, 2008

Page 21 of 146

REJ03B0224-0101

455A Group

PROGRAM MEMORY (ROM)

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

composed of 10 bits. ROM is separated every 128 words by the

unit of page (addresses 0 to 127). Table 8 shows the ROM size

and pages. Figure 21 shows the ROM map of M3455AGD.

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

interrupt addresses (Figure 22). 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 9 to 0) of all addresses can be used as data

areas with the TABP p instruction.

Note1.In the initial state, data in pages 0 to 63 can be

refered with the TABP instruction. Data in pages

64 to 95 can be refferd with the TABP p instruction

after the SBK instruction is executed.Data in

pages 0 to 63 can be referred with the TABP p

instruction after the RBK instruction is executed.

ROM Code Protect Address

When selecting the protect b it wr ite by using a serial

programmer or selecting protect enabled for writing shipment by

Renesas Technology corp., reading or writing from/to QzROM is

disabled by a serial programmer.

As for the QzROM product in blank, the ROM code is protected

by selecting the protect bit write at ROM writing with a serial

programmer.

As for the QzROM product shipped after writing, whether the

ROM code protect is used or not can be selected as ROM option

setup (“MASK option” written in the mask file converter) when

ordering.

Fig 21. ROM map of M3455AGC

Fig 22. Page 1 (addresses 008016 to 00FF16) structure

Table 8

ROM size and pages

Part number

ROM (PROM) size

(

× 10 bits)

Pages

M3455AG8

8192 words

64 (0 to 63)

M3455AGC (Note 1) 12288 words

96 (0 to 95)

Interrupt address page

Subroutine special page

000016

007F16

008016

00FF16

010016

017F16

018016

2FFF16

Page 95

Page 0

Page 1

Page 2

Page 3

9 8

76543

210

00FF16

008C16

008A16

008816

Timer 2 interrupt address

008616

Timer 1 interrupt address

008416

008216

External 0 interrupt address

008016

6543

210

Timer 3 interrupt address

008E16

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