[pups] 2.11BSD boot hangs.

[Steven M. Schultz]

Hi -

> From jkunz at unixag-kl.fh-kl.de Mon Feb 26 13:16:40 2001
> > 	There is a jumper (I forget which one) that enables/disables the
> > 	'halt' instruction. 
> BINGO! Pulling W5 solved the problem. But then I seted it again to
> double check. (I changed location today and took only the cards and
> disk with me.) In the "new" BA23 the system runs even with the W5

	Years ago I was completely suprised that 'halt' in kernel mode did 
	not work and the system simply continued executing the next instruction.

> jumper installed. Then I noticed the different setting of the front
> panel DIP swich. The upper switch is off and the lower on. The switches
> of the other cabinet are both on. If I boot the machine with W5
> installed and the upper switch on it hangs. It continues to run
> immediately if it is switched off. What is the purpose of this
> switches? 

	I suspect that one of the switches enables the line frequency clock.
	With out a clock running things will work (at least minimally) as
	long as there are some interrupts happening.   

	I vaguely remember that some systems (11/23?) had an externally 
	enabled clock and if that switch was not set correctly the OS could
	be installed but the system would "hang" later on due to no context
	switch scheduling.

> OK. The machine is currently un-tar-ing /usr... :-)))

	Fantastic!

> Ahh, and an other question: Can the RT11 bootstrap listed in 
> http://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/bootstraps/mscp_rt11.txt
> be used to boot 2.11BSD? I have no bootstrap ROM card. (Emanuel, hint,

	I think it will work.   2.11 is expecting the registers to contain
	the following:

		R0 = unit number
		R1 = CSR of booting controller

	as long as those are set it should not matter what bootcode is used.

	Steven Schultz
	sms at moe.2bsd.com

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