Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!ucbvax!hplabs!hpfcdc!perry
From: perry@hpfcdc.HP.COM (Perry Scott)
Newsgroups: comp.sys.hp
Subject: Re: How do you get to console debug mode on HP-9000/300 ?
Message-ID: <5570238@hpfcdc.HP.COM>
Date: 14 Jul 89 22:07:51 GMT
References: <2434@cpoint.UUCP>
Organization: HP Ft. Collins, Co.
Lines: 11

>If there *is* a debugger (or a monitor mode) hidden in the boot ROM
>code, I'd love to play with it.

SYSDEBUG resides in main memory.  It isn't part of the Boot ROM.  The
procedure is to boot the debugger instead of the kernel, then boot the
kernel from the debugger.  The debugger grabs a piece of RAM, then
covers itself up by telling the system that there isn't as much memory
as previously thought.  The kernel, meanwhile, happily chugs along with
this inert area of RAM lying about.

Perry Scott