Motorola MVME162 manual ROMboot

ROMboot

Caution

Although streaming tape can be used to autoboot, the same power supply must be connected to the streaming tape drive, controller, and the MVME162. At power-up, the tape controller will position the streaming tape to load point where the volume ID can correctly be read and used.

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If, however, the MVME162 loses power but the controller does not, and the tape happens to be at load point, the sequences of commands required (attach and rewind) cannot be given to the controller and autoboot will not be successful.

ROMboot

As shipped from the factory, 162Bug occupies the first half of the Flash memory. This leaves the second half of the Flash memory and the PROM socket (U47) available for your use. The 162Bug is also available in PROM if your application requires all of the Flash memory. Contact your Motorola sales office for assistance. This function is configured/enabled by the Environment (ENV) command (refer to Appendix A) and executed at power-up (optionally also at reset) or by the RB command assuming there is valid code in the memory devices (or optionally elsewhere on the module 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 NORB command disables the function.

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

a.Power must have just been applied (but the ENV command can change this to also respond to any reset).

b.Your routine must be located within the MVME162 Flash/PROM memory map (but the ENV command can change this to any other portion of the onboard memory, or even offboard VMEbus memory).

c.The ASCII string "BOOT" must be located within the specified memory range.

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

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

MVME162IG/D2 3-7