GMS84512 Datasheet, PDF (18/123 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCOMPUTER

GMS 84512 / 84524
2.1.5. Program Counter ( PC )
l Program counter is a 16-bit counter consisted of 8-bit register PCH and PCL.
l Addressing space is 64K bytes.
l In reset state, Reset routine address in address FFFFH and FFFEH enter into PC.
2.1.6. Program Status Word( PSW )
l PSW is an 8-bit register.
l Consisted of the flags to show the post state of operation and the flags determining
the CPU operation, initialized as 00H in reset state.
PSW
7
6
5
4
3
2
1
0
NVGBH
I
ZC
¨ ç Carry Flag ( C )
l After operation, set when there is a carry from bit7 of ALU or there is not a borrow.
l Set by SETC and clear by CLRC.
l Executable as 1-bit accumulator.
l Branch condition flag of BCS, BCC.
¨ è Zero Flag ( Z )
l After operation also including 16-bit operation, set if the result is “0”.
l Branch condition flag of BEQ, BNE.
¨ é Interrupt Enable Flag ( I )
l Master enable flag of interrupt except for RST(reset).
l Set and cleared by EI, DI .
¨ ê Half Carry Flag ( H )
l After operation, set when there is a carry from bit3 of ALU or there is not a borrow
from bit4 of ALU.
l Can not be set by any instruction.
l Cleared by CLRV instruction like V flag.
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