z86e72 ZiLOG Semiconductor, z86e72 Datasheet - Page 41

• Manufacturer Part Number: z86e72
• Description: Otp Microcontroller
• Manufacturer: ZiLOG Semiconductor

PS008704-0507
RAM
Extended Data RAM
The Z86E72 has a 768-byte RAM; 256 bytes make up the register file. The
remaining 512 bytes make up the Extended Data RAM. The Z86E73 has just the
256 bytes of the register file.
The Extended Data RAM of the Z86E72 occupies the address range FE00H–
FFFFH (512 bytes). This range of addresses FD00H–FFFFH cannot be used to
directly read from or write to external memory. Accessing the Extended Data RAM
is accomplished by using LDE or LDEI instructions. Port 1 and Port 0 are free to
be set as I/O or ADDR/DATA modes; expect high-impedance when accessing
Extended Data RAM. In addition, if the external memory uses the same address
range of the Extended Data RAM, it can be used as the External Stack only.
Exercise caution when using extended data RAM (not Z8 RAM) on the Z86E72
OTP microcontroller. Extended RAM spaces FF0C–FF0F, FF10, FE0C–FE0F,
and FE10 are reserved. Do not use these extended RAM locations.
After RESET
(Upper Byte)
(Lower Byte)
First Byte of
Location of
Instruction
Executed
Interrupt
Interrupt
Vector
Vector
16384
65535
12
10
11
9
8
7
6
5
4
3
2
1
0
Figure 20. Program Memory Map
Reset Start Address
On-Chip ROM
External ROM
Reserved
Reserved
IRQ4
IRQ3
IRQ2
IRQ1
IRQ0
IRQ4
IRQ3
IRQ2
IRQ1
IRQ0
OTP Microcontroller
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