Z86L04 Datasheet, PDF (15/26 Pages) Zilog, Inc. – Z8 8-Bit Cost-Effective Microcontrollers

Zilog
Program Memory. The Z8 addresses up to 1024,2048
bytes of internal program memory (Figure 11). The first 12
bytes of program memory are reserved for the interrupt
vectors. These locations contain six 16-bit vectors that cor-
respond to the six available interrupts. Bytes
0-1023/0-2047 are on-chip mask programmable ROM.
1024/2047
Location of
First Byte of
Instruction
Executed
After RESET 12
11
10
9
8
7
Interrupt
Vector ₆
(Lower Byte)
5
4
Interrupt
Vector ₃
(Upper Byte)
2
1
0
On-Chip
ROM
IRQ5
IRQ5
IRQ4
IRQ4
IRQ3
IRQ3
IRQ2
IRQ2
IRQ1
IRQ1
IRQ0
IRQ0
Figure 11. Program Memory Map
Register File. The Register File consists of three I/O port
registers, 61 general-purpose registers, and 12 control
and status registers R0-R3, R4-R127 and R241-R255, re-
spectively (Figure 12). General-purpose registers occupy
the 04H to 7FH address space. I/O ports are mapped as
per the existing CMOS Z8. The instructions can access
registers directly or indirectly through an 8-bit address
field. This allows short 4-bit register addressing using the
Register Pointer. In the 4-bit mode, the register file is divid-
ed into eight working register groups, each occupying 16
continuous locations. The Register Pointer (Figure 13) ad-
dresses the starting location of the active working-register
group.
Z86L04/L08
Z8 8-Bit Cost-Effective Microcontrollers
Location
Indentifiers
255
Stack Pointer (Bits 7-0)
SPL
1
254
General Purpose GPR
253
Register Pointer
RP
252
Program Control Flags
Flags
251
Interrupt Mask Register
IMR
250
Interrupt Request Register
IRQ
249
Interrupt Priority Register
IPR
248
Ports 0-1 Mode
P01M
247
Port 3 Mode
P3M
246
Port 2 Mode
P2M
245
To Prescaler
PRE0
244
Timer/Counter0
T0
243
T1 Prescaler
PRE1
242
Timer/Counter1
T1
241
Timer Mode
TMR
240
Not Implemented
128
127
General Purpose
Registers
4
3
Port 3
P3
2
Port 2
P2
1
Reserved
P1
0
Port 0
P0
Figure 12. Register File
DS97LVO0901
PRELIMINARY
15