Nokia NSE-3 SERIES, Service Manual

Page: 49 / 217

PAMS
Technical Documentation
NSE–3
System Module
Page 3 – 43
Original 11/97
Memories
The MCU program code resides in an external flash program memory,
which size is 8 Mbits (512kx16bit). The MCU work (data) memory size is
512kbits (64kx8bit). A serial EEPROM is used for storing the system and
tuning parameters, user settings and selections, a scratch pad and a
short code memory. The EEPROM size is 64kbits (8kx8bit).
The BusController (BUSC) section in the MAD decodes the chip select
signals for the external memory devices and the system logic. BUSC con-
trols internal and external bus drivers and multiplexers connected to the
MCU data bus. The MCU address space is divided into access areas with
separate chip select signals. BUSC supports a programmable number of
wait states for each memory range.
Program Memory
The MCU program code resides in the program memory. The program
memory size is 8 Mbits (512kx16bit).
The flash memory has a power down pin that should be kept low, during
the power up phase of the flash to ensure that the device is powered up
in the correct state, read only. The power down pin is utilized in the sys-
tem sleep mode by connecting the ExtSysResetX to the flash power down
pin to minimize the flash power consumption during the sleep.
SRAM Memory
The work memory is a static ram of size 512k (64kx8) in a shrink TSOP32
package. The work memory is supplied from the common baseband VBB
voltage and the memory contents are lost when the baseband voltage is
switched off. All retainable data should be stored into the EEPROM (or
flash) when the phone is powered down.
EEPROM Memory
An EEPROM is used for a nonvolatile data memory to store the tuning
parameters and phone setup information. The short code memory for
storing user defined information is also implemented in the EEPROM.
The EEPROM size is 8kbytes. The memory is accessed through a serial
bus and the default package is SO8.