Front panel switches - what did they do?

[Sean Conner]

It was thus said that the Great Swift Griggs once stated:
> On Tue, 24 May 2016, Charles Anthony wrote:

> > The data switches would be examined by the operating system during boot 
> > to enable debugging (pause at certain points during boot, eg).
> 
> I wish OS's still had something like this sometimes. Using a debugger over 
> serial, there are times when I'd like to step through code or stop the 
> whole kit-and-kaboodle. However, there are so many timers running in OS's 
> these days a lot of the time that sort of thing causes major pain, 
> especially with certain problematic drivers.

  The Amiga has a minimal debugger embedded in the ROM that ran over the
serial port (9600 8n1).  It would automatically become active when a Guru
Meditation (similar to a Unix kernel panic, or the Mac bomb, or the Windows
Blue Screen of Death) but you could get to it at other times as well (I
played around with it a bit).  The debugger is *very* minimal (hex dumps of
memory and registers, you could modify memory and registers, resume, etc).

> > Some of the mainframes had hundreds and hundreds of lights, detailing 
> > the internal state of the machine; mostly of interest to field 
> > engineers.
> 
> It probably still impressed the suits when they walked the data center. 
> I've done data center tours with row after row of HP or Dell x86 servers 
> and it's not much to look at. 

  The original Connection Machine had one LED per CPU (max 65,536).  You
could get some pretty impressive visuals out of that one.

  -spc