z89138 ZiLOG Semiconductor, z89138 Datasheet - Page 30

• Manufacturer Part Number: z89138
• Description: Voice Processing Controllers
• Manufacturer: ZiLOG Semiconductor

Z89138/Z89139
Voice Processing Controllers
Z8 FUNCTIONAL DESCRIPTION
The Z8 core of the Z89138/139 incorporates special func-
tions to enhance the Z8’s application in a variety of voice-
processing applications.
Reset. The device is reset in one of the following condi-
tions:
Program Memory. The Z8 addresses up to 24 KB of inter-
nal program memory and 40 KB external memory (Figure
17). The first 12 bytes of program memory are reserved for
the interrupt vectors. These locations contain six 16-bit
vectors which correspond to the five user interrupts and
one DSP interrupt. Byte 12 to byte 24575 consist of on-
chip mask-programmed ROM. At addresses 24576 and
greater the Z8 executes external program memory. In
ROMless mode, the Z8 will execute external program
memory beginning at byte 12 and continuing through byte
65535.
30
Power-On Reset
Watch-Dog Timer
Stop-Mode Recovery Source
External Reset
(Lower Byte)
(Upper Byte)
After RESET
First Byte of
Location of
Instruction
Executed
Interrupt
Interrupt
Vector
Vector
Figure 17. Program Memory
65535
24575
12
11
10
9
8
7
6
5
4
3
2
1
0
ROM and RAM
In ROM Mode
On-Chip
External
ROM
IRQ5
IRQ5
IRQ4
IRQ4
IRQ3
IRQ3
IRQ2
IRQ2
IRQ1
IRQ1
IRQ0
IRQ0
P R E L I M I N A R Y
ROM Protect. The 24 KB of internal program memory for
the Z8 is mask programmable. A ROM protect feature pre-
vents “dumping” of the ROM contents of Program Memory
by inhibiting execution of LDC, LDCI, LDE, and LDEI in-
structions. The ROM Protect option is mask-programma-
ble, to be selected by the customer at the time the ROM
code is submitted.
Data Memory (/DM). In ROM Mode, the Z8 can address
up to 40 KB of external data memory beginning at location
24576 (Figure 18). In ROMless mode, the Z8 can address
the full 64 KB of external data memory beginning at loca-
tion 12. External data memory can be included with, or
separated from, the external program memory space.
/DM, an optional I/O function that can be programmed to
appear on Port 34, is used to distinguish between data and
program memory space. The state of the /DM signal is
controlled by the type of instruction being executed. An
LDC opcode references PROGRAM (/DM inactive) mem-
ory, and an LDE instruction references data (/DM active
Low) memory (Figure 18).
24575
65535
Figure 18. Data Memory Map
0
Not Addressable
(In ROM Mode)
External
Memory
Data
DS97TAD0201
Zilog