Zilog Z80380 Manual do Utilizador descarregar pdf (Página 83)

5-49

Z380

™

USER'S MANUAL

ZILOG

DC-8297-03

ENABLE INTERRUPTS

EI [n]

Operation: if (n is present) then begin

for i=1 to 4 begin

if (n(i) = 1) then begin

IER(i-1) ← 1

end

if (n(0) = 1) then begin

SR(5) ← 1

end

else begin

SR(5) ← 1

end

If an argument is present, enable the selected interrupts by setting the appropriate enable

bits in the Interrupt Enable Register, and then set the Interrupt Enable Flag (IEF1) in the

Select Register (SR) if the least-significant bit of the argument is set, enabling maskable

interrupts. Bits 7-5 of the argument are ignored.

If no argument is present, IEF1 in the SR is set to 1, enabling maskable interrupts.

Note that during the execution of this instruction and the following instruction, maskable

interrupts are not sampled.

Flags: S: Unaffected

Z: Unaffected

H: Unaffected

V: Unaffected

N: Unaffected

C: Unaffected

Addressing Execute

Mode Syntax Instruction Format Time Note

EI 11111011 2

EI n 11011101 11111011 —n—— 2

1 2 ... 78 79 80 81 82 83 84 85 86 87 88 ... 267 268

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Zilog Z80380 Manual do Utilizador Página 83