Autoboot

Debugger General Information

Note that the MVME197LE also contains a parallel port. To use a parallel device, such as a printer, with the MVME197LE, connect it to the “printer” port at P2 through an MVME712X transition module. Refer to the MVME197LE, MVME197DP, and MVME197SP Single Board Computers

3Programmer’s Reference Guide for some possible connection diagrams. However, you could also use a module such as the MVME335 for a parallel port connection.

5.Power up the system. 197Bug executes some self-checks and displays the debugger prompt “197-Bug>” (if 197Bug is in Board Mode). However, if the ENV command has put 197Bug in System Mode, the system performs a self test and tries to autoboot. Refer to the ENV and MENU commands. They are listed in Table 4-1.

If the confidence test fails, the test is aborted when the first fault is encountered. If possible, an appropriate message is displayed, and control then returns to the menu.

Autoboot is a software routine that is contained in the 197Bug to provide an independent mechanism for booting an operating system. This autoboot routine automatically scans for controllers and devices in a specified sequence until a valid bootable device containing a boot media is found or the list is exhausted. If a valid bootable device is found, a boot from that device is started. The controller scanning sequence goes from the lowest controller Logical Unit Number (LUN) detected to the highest LUN detected. (Refer to Appendix B for default LUNs).

At power-up, Autoboot is enabled, and providing the drive and controller numbers encountered are valid, the following message is displayed upon the system console:

“Autoboot in progress... To abort hit <BREAK>”

Following this message there is approximately a thirty-second delay while the debug firmware waits for the various controllers and drives to come up to speed. Then the actual I/O is begun: the program pointed to within the volume ID of the media specified is loaded into RAM and control passed to it. If, however, during this time the user wants to gain control without Autoboot, the <BREAK> key or the software ABORT or RESET switches can be pressed.

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.

3-4	Installation Guide