Motorola MVME162LX User Manual

ROMboot

3-9

As shipped from the factory, 162Bug occupies an EPROM installed 
in socket XU2. This leaves one socket (XU1) and the Flash memory 
available for your use. Contact your Motorola sales office for 
assistance. This function is configured/enabled by the 
Environment (

) command (refer to Appendix A) and executed 

at powerup (optionally also at reset) or by the 

 command 

assuming there is valid code in the memory devices (or optionally 
elsewhere on the board or VMEbus) to support it. If ROMboot code 
is installed, a user-written routine is given control (if the routine 
meets the format requirements). One use of ROMboot might be 
resetting SYSFAIL* on an unintelligent controller module. The 

 command disables the function. 

For a user's ROMboot module to gain control through the 
ROMboot linkage, four requirements must be met: 

❏

Power must have just been applied (but the 

 command 

can change this to also respond to any reset). 

❏

Your routine must be located within the MVME162LX 
Flash/PROM memory map (but the 

 command can 

change this to any other portion of the onboard memory, or 
even offboard VMEbus memory). 

❏

The ASCII string ÔÔBOOTÕÕ must be located within the 
specified memory range. 

❏

Your routine must pass a checksum test, which ensures that 
this routine was really intended to receive control at 
powerup. 

For complete details on how to use ROMboot, refer to the 
Debugging Package for Motorola 68K CISC CPUs User's Manual.