Operation; Decryption Module; Brief Description; -Ram Module - Mitel SX-200 Practices

Circuit Card Descriptions
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Decryption Module to enable use of protected software
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Fault detection hardware to monitor PCM clock and processor sanity (watchdog)
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System Reset switch (front panel).
Operation
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The correct Decryption Module must be installed, or the disk software will not run,
At power-up the Main Control Card is held in reset for about I second after the. power
,supply voltages reach their normal levels. After reset, the processor first runs the
software contained in its EPROM. This consists of tests for the RAM memory, the CPU
and the DMA controller. A routine to load the system software into RAM from disk is run
only after all preliminary tests have been passed.
The Main Control Card may also be reset via the push button switch behind the front
panel of the card near the top. Reset invokes Power Fail Transfer, which remains in
effect until the system software has been loaded from disk.
DECRYPTION MODULE
Brief Description
2.4
The Decryption Module plugs into the lower front corner of the Main Control Card.
The Decryption Module must be present during power-up and system operation.
Figure 2-l shows the location of the Decryption Module on the Main Control Card.
Operation
The Decryption Module is written to and read from constantly by the system software,
If there is a mismatch between the module and the software, the software will not run,
-RAM MODULE
Brief Description
2.5
The RAM Module carries the dynamic memory required for program storage and call
processing work areas. It plugs into a 96pin DIN connector on the lower part of the
Main Control Card. Mechanical support is provided by standoffs. The board
measures 25.9 mm x 14.5 mm high (10.6 in. x 5.7 in.).
Parity is checked on all read and refresh cycles by circuitry on the Main Control Card,
If the parity logic detects an error, it logs it in CMOS RAM and invokes a system reset
via software.
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Revision
0 9109-096-I 25-NA Issue
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