5

* This specification are subject to be changed without notice.

EM73201

4-BIT MICRO-CONTROLLER FOR GENERAL PURPOSE PRODUCT

Preliminary

7.20.1999

ZERO- PAGE:

From 00h to 0Fh is the location of zero-page. It is used as the pointer in zero-page addressing mode for the

instruction of "STD #k,y; ADD #k,y; CLR y,b; CMP k,y".

PROGRAM EXAMPLE:

To wirte immediate data "07h" to address "03h" of RAM and to clear bit 2 of RAM.

STD #07h, 03h ; RAM[03] ← 07h

CLR 0Eh,2 ; RAM[0Eh]

STACK:

There are 13 - level (maximum) stack for user using for subroutine (including interrupt and CALL). User

can assign any level be the starting stack by giving the level number to stack pointer (SP).

When user using any instruction of CALL or subroutine, before entry the subroutine, the previous PC address

will be saved into stack until return from those subroutines, the PC value will be restored by the data saved

in stack.

DATA AREA:

Except the special area used by user, the whole RAM can be used as data area for storing and loading general

data.

ADDRESSING MODE

(1) Indirect addressing mode:

Indirect addressing mode indicates the RAM address by specified HL register.

STAM ; RAM[HL] ← Acc

(2) Direct addressing mode:

Direct addressing mode indicates the RAM address by immediate data.

STAMI

; RAM[30] ← 6h

LDAXI

; ACC ← 5h

STAM

; RAM[31] ← 5h

:

ORG 777h

DATA 56h;

:

DATA RAM ( 52-nibble )

There is total 52 - nibble data RAM from address 00 to 33h

Data RAM includes 3 parts: zero page region, stacks and data area.

Increment

Address

20h - 2Fh

30h - 33h

Level 0

Level 4

Level 8

Level 12

Level 1

Level 5

Level 9

Level 2

Level 6

Level 10

Level 3

Level 7

Level 11

00h - 0Fh

10h - 1Fh

Stack

Zero-page