Z86E30/E31/E40
Z8 4K OTP Microcontroller
Zilog
EPROM Protect. When in ROM Protect Mode, and exe-
cuting out of External Program Memory, instructions LDC,
LDCI, LDE, and LDEI cannot read Internal Program Mem-
ory.
location 4096. In ROMless mode, the Z86E40 can address
up to 64 KB of data memory. External data memory may
be included with, or separated from, the external program
memory space. /DM, an optional I/O function that can be
programmed to appear on pin P34, is used to distinguish
between data and program memory space (Figure 23).
The state of the /DM signal is controlled by the type of in-
struction being executed. An LDC opcode references
PROGRAM (/DM inactive) memory, and an LDE instruc-
tion references data (/DM active Low) memory.
1
When in ROM Protect Mode and executing out of Internal
Program Memory, instructions LDC, LDCI, LDE, and LDEI
can read Internal Program Memory.
Data Memory (/DM). In EPROM Mode, the Z86E40 can
address up to 60 KB of external data memory beginning at
EPROM
ROMless
65535
External
Data
External
Data
Memory
Memory
4096
4095
Not Addressable
0
Figure 23. Data Memory Map
DS97Z8X0500
P R E L I M I N A R Y
33
ZILOG [ ZILOG, INC. ]
