UPD7554AA 데이터 시트보기 (PDF) - NEC => Renesas Technology

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UPD7554AA

4-BIT SINGLE-CHIP MICROCOMPUTER

NEC => Renesas Technology 

µPD7554A, 7554A(A)

2.3 PROGRAM MEMORY (ROM): 1024 WORDS × 8BITS

The program memory is a mask programmable ROM of 1024 word × 8 bits configuration. It is addressed by the

program counter.

The program memory stores programs.

Address 000H is the reset start address.

Fig. 2-4 Program Memory Map

(0) 000H

Reset Start

(1023) 3FFH

2.4 GENERAL REGISTER

General registers H (with two bits) and L (with four bits) operate individually. They also form a pair register HL

(H: high order and L: low order) to serve as a data pointer for addressing the data memory.

Fig. 2-5 General Register Configuration

1

0

3

0

H

L

The L register is also used to specify I/O ports and the mode register when an input/output instruction (IPL or

OPL) is executed. It also used to specify the bits of a port when the SPBL or RPBL instruction is executed.

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