[SunRescue] 3/160 and Terminals

[Robert D. Keys]

> Hi,
> 	Another quick question.  Iv'e heard there is a right order for
> plugging in and switching on when using a vt100 terminal with a sun 3/160.
> I believe that getting it wrong can blow the ports so can anyone tell me the
> right way to do it.

I run several of the old VME suns (3/110, 4/110, 3/160, 3/200), and use
the following order:

  poweron ---- terminals and peripheral drive cases and printers first
               then the cpu chassis.

  poweroff --- peripheral drive cases first, the terminals and printers,
               then the cpu chassis.

I don't use a real VT100 terminal, and memory vaguely tells me that
on some systems (don't know the exact types right off), the VT100 power
can blow chips.  I always use only 3 wire (T/R/G) hookups, so that may
not be a problem, if no other signal lines are present.  My terminals
are all WYSE, PC/kermit, or Heathkit/Zenith things.

The old full-page sun docs suggest a slightly different order, but
that always seemed to electronically make no sense to me.  On poweron my
memory suggests that they recommend cpu on first, and peripherals second.
I have always done it the other way around because I want to make sure
the CPU sees the correct signals on poweron so the hardware and software
does not get into conflict over signals being presented to the cpu during
the transitions in peripheral signal lines on powerup.  Along the same
thinking, I always make sure peripherial drives are spinning at speed
and cycled to the line (from the boot posts), before turning on the
CPU.

That is all I know.  Maybe others can fill us in on any other details.
I am sure there are historic or engineering reasons for how it should
be done, and that can only be good information to share.

Bob Keys