user manual

Booting and Restarting 187Bug

4-7

4. Following this message there is a delay to allow you an

opportunity to abort the Autoboot process if you wish. To

gain control without Autoboot, you can press the

BREAK key

or the software

ABORT or RESET switches.

5. Then the actual I/O begins: the program pointed to within

the volume ID of the media specified is loaded into RAM and

control passed to it.

Autoboot is controlled by parameters contained in the ENV

command. These parameters allow the selection of specific boot

devices and files, and allow programming of the Boot delay. Refer

to the ENV command in Appendix A for more details.

ROMboot

There are two spare EPROM sockets, XU3 and XU4, available to

carry user-programmed EPROMs. Therefore, you do not have to

reprogram the 187Bug EPROMs in order to implement the

ROMboot feature.

One use of ROMboot might be resetting SYSFAIL* on an

unintelligent controller module. The NORB command disables the

function.

ROMboot Sequence

1. ROMboot is configured/enabled and executed at powerup

(optionally also at reset) in one of two ways:

a. By the Environment (ENV) command (refer to

Appendix A)

b. By the RB command assuming there is valid code in the

EPROMs (or optionally elsewhere on the module or

VMEbus) to support it.

2. If ROMboot code is installed, a user-written routine is given

control (if the routine meets the format requirements).