Z86C21 Datasheet, PDF (26/35 Pages) Zilog, Inc. – 8K ROM Z8 CMOS MICROCONTROLLER

Z8 CONTROL REGISTER DIAGRAMS (Continued)
R250 IRQ
D7 D6 D5 D4 D3 D2 D1 D0
R253 RP
D7 D6 D5 D4 D3 D2 D1 D0
IRQ0 = P32 Input (D0 = IRQ0)
IRQ1 = P33 Input
IRQ2 = P31 Input
IRQ3 = P30 Input, Serial Input
IRQ4 = T0 Serial Output
IRQ5 = T1
Reserved (Must be 0)
Z86C21 MCU
WITH 8K ROM
0 Reserved (Must be 0)
r4
r5
Register Pointer
r6
r7
Figure 33. Interrupt Request Register
(FA : Read/Write)
H
Figure 36. Register Pointer Register
(FD : Read/Write)
H
R251 IMR
D7 D6 D5 D4 D3 D2 D1 D0
1 Enables IRQ5-IRQ0
(D0 = IRQ0)
1 Enables RAM Protect
1 Enables Interrupts
Figure 34. Interrupt Mask Register
(FB : Read/Write)
H
R252 FLAGS
D7 D6 D5 D4 D3 D2 D1 D0
User Flag F1
User Flag F2
Half Carry Flag
Decimal Adjust Flag
Overflow Flag
Sign Flag
Zero Flag
Carry Flag
Figure 35. Flag Register
(FC : Read/Write)
H
R254 SPH
D7 D6 D5 D4 D3 D2 D1 D0
Stack Pointer Upper
Byte (SP15 - SP8)
Figure 37. Stack Pointer Register
(FE : Read/Write)
H
R255 SPL
D7 D6 D5 D4 D3 D2 D1 D0
Stack Pointer Lower
Byte (SP7 - SP0)
Figure 38. Stack Pointer Register
(FF : Read/Write)
H
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