ZiLOG Z8 Technical Manual

Control Registers
Registers
(Continued)
R248 POIM
Port 0 and 1 Mode Register
(F8H; Write Only)
B-2
PO.-PO, MODE:] ~-r pOo-po, MODE
OUTPUT = 00 ~ L 00 = OUTPUT
INPUT = 01 01 = INPUT
A
12
-A
15
= 1X 1X = A
,
-A'1
EXTERNAL MEMORY TIMING STACK SELECTION
NORMAL = 0 0 D EXTERNAL
EXTENDED
= 1 1 = INTERNAL
Pl
o
-Pl, MODE
00 = BYTE OUTPUT
01 = BYTE IN PUT
10 = ADo-AD,
11 = HIGH·IMPEDANCE ADo-ADT,
AS, OS, Rffl, Aa-All, A12-A'5
IF SELECTED
R2491PR
Interrupt Priority Register
(F9H; Write Only)
I~I~I~I~I~I~I~I~I
,~,,,,,:J ! I II' "","",,,,,",,,,,,m
RESERVED = 000
IRQ3,
IRQS PRIORITY (GROUP A) C > A > B = 001
o = IRQS > IRQ3 A > B > C = 010
1 = IRQ3 > IRQS A > C > B = 011
B > C > A = 100
IRQO, IRQ2 PRIORITY (GROUP B) C > B > A = 101
o = IRQ2 > IRQO B > A > C = 110
1 = IRQO > IRQ2 RESERVED = 111
IRQ1, IRQ4 PRIORITY (GROUP C)
o = IRQl > IRQ4
1 = IRQ4 > IRQl
R250 IRQ
Interrupt Request Register
(FAH; Read/Write)
I~I~I~I~I~I~I~I~I
RESERVED T c= IRQO
IRQl
IRQ2
IRQ3
IRQ4
IRQS
R251lMR
Interrupt Mask Register
(FBH; Read/Write)
10,1 0,1 Os 1
0
.1
0
,1
0
,1 0, I Do I
P3, INPUT (Do = IRQO)
P331NPUT
P3,INPUT
P30 INPUT, SERIAL INPUT
To, SERIAL OUTPUT
T,
I'
c= 1 ENABLES IRQO-IRQS
(Do = IRQO)
'-------- RESERVED
'---------1 ENABLES INTERRUPTS
REGISTER
POINTER
R252 FLAGS
Flag Register
(FCH; Read/Write)
LUSER FLAG F2
HALF CARRY FLAG
DECIMAL ADJUST FLAG
OVERFLOW FLAG
~~~
I LUSER FLAG Fl
R253 RP
Register Pointer
(FDH; Read/Write)
SIGN FLAG
ZERO FLAG
CARRY FLAG
C=DON'T CARE
R254 SPH
Stack Pointer
(FEH; Read/Write)
I 0,1 0.1 Os I 0.1 0,1 0,1 0, I Do I
R255 SPL
Stack Pointer
(FFH; Read/Write)
2037-014

ZiLOG Z8 Specifications

General

Brand	ZiLOG
Model	Z8
Category	Desktop
Language	English