M34282E2GP MITSUBISHI [Mitsubishi Electric Semiconductor], M34282E2GP Datasheet - Page 8

• Manufacturer Part Number: M34282E2GP
• Description: SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

(8) Program counter (PC)
(9) Data pointer (DP)
8
Program counter (PC) is used to specify a ROM address (page
and address). It determines a sequence in which instructions
stored in ROM are read. It is a binary counter that increments
the number of instruction bytes each time an instruction is
executed. However, the value changes to a specified address
when branch instructions, subroutine call instructions, return
instructions, or the table reference instruction (TABP p) is
executed.
Program counter consists of PC
which specifies to a ROM page and PC
specifies an address within a page. After it reaches the last
address (address 127) of a page, it specifies address 0 of the
next page (Figure 7).
Make sure that the PC
the built-in ROM.
Data pointer (DP) is used to specify a RAM address and
consists of registers X and Y. Register X specifies a file and
register Y specifies a RAM digit (Figure 8).
Register Y is also used to specify the port D bit position.
When using port D, set the port D bit position to register Y
certainly and execute the SD, RD, or SZD instruction (Figure
9).
H
does not exceed after the last page of
H
(most significant bit to bit 7)
L
(bits 6 to 0) which
MITSUBISHI
ELECTRIC
Fig. 7 Program counter (PC) structure
Fig. 8 Data pointer (DP) structure
Fig. 9 SD instruction execution example
Register Y (4)
0 1 0 1
p
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
Register X (2)
Specifying bit position
Specifying
3
p
X
page
PC
2
1
Data pointer (DP)
p
Program counter (PC)
H
X
1
0
p
MITSUBISHI MICROCOMPUTERS
0
Y
Register Y (4)
3
D
a
Y
Specifying address
7
6
2
a
Specifying RAM file
Port D output latch
Y
5
1
Set
a
D
1
4
PC
Y
5
0
a
3
L
Specifying
RAM digit
4282 Group
a
2
a
1
a
0
D
0