UPD7564A Datasheet, PDF (15/56 Pages) NEC – 4-BIT SINGLE-CHIP MICROCOMPUTER

µPD7564A, 7564A(A)
2.3 PROGRAM MEMORY (ROM): 1024 WORDS × 8 BITS
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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