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Memory Units
EPROM Unit
EEPROM Unit
RAM Unit
Switches on Memory
Units
Battery Failure Flag
20
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The data that you wish to store in an EPROM Unit must first be written to an
EPROM Chip, using the PROM Writer. Then the EPROM Chip must be mounted
to the inside of the EPROM Unit. Once this has been done, the data cannot be
changed. In addition, the data will be retained indefinitely when the power is
turned OFF.
Data can be stored in the EEPROM Unit while the Unit is mounted to the PC. The
data is retained indefinitely when the power is turned OFF.
Data can be randomly written to and read from the RAM Unit. However, the Unit
requires battery or capacitor back-up in order to retain the information when the
power is OFF. Units with battery back-up can retain their data for approximately
five years at room temperature (25°C). Units with capacitor back-up retain their
data for approximately 20 days at room temperature, but the length of time va-
ries with temperature as shown below.
20
Capacitor
back-up time
(days)
10
7
1
25
Two switches are provided on Memory Units, as shown below.
1
2
ON OFF
SW1 (the write enable switch) only has an effect if the Unit is a RAM Unit or EE-
PROM Unit. Peripheral devices can only write data to these Memory Units if
SW1 is ON. When you wish to write data to this Memory Unit, make sure SW1 is
set to the ON position. After you have finished writing the data to the Memory
Unit, turn SW1 to the OFF position so that the data will be protected from any
further changes. If you try to write data to the Memory Unit while SW1 is in the
OFF position, the message "DISABLED ROM" will appear on the Programming
Console.
SW2 Selects what operating mode the PC will be in when power is applied to the
System. If there is no peripheral device connected to the CPU, the PC will enter
RUN mode when power is applied. If a Programming Console is connected to
the CPU, the PC will enter the mode that the Programming Console is set to. If a
peripheral device other than the Programming Console is connected to the
CPU, the PC will enter the mode specified by SW2.
The C200H-CPU11-E, unlike the other two CPU models, has an additional bat-
tery connected to the CPU. A flag, assigned to the bits listed in the following
table, indicates where battery failure occurred (in the RAM Unit or in the CPU)
and in which Unit.
50
80
Ambient temperature (°C)
Write-enable switch
(SW1)
Initial mode selector
(SW2)
Section
2-6
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