Re: DECstation 2100: power trouble?

["Maciej W. Rozycki" <macro%orcam.me.uk@localhost>]

On Fri, 17 Apr 2026, Mouse wrote:

> >> I don't know why I didn't succeed before.  I must have not done
> >> whatever magic sequence got it past getting stuck at ef before.
> 
> > It might have just needed a little time to "wake up". :-)
> 
> I speculate that it's thermal.  There are two chips that get hot (more
> than "warm") to the touch: the CPU and a (heatsinked!) chip on the
> other side of the CPU from the RAM slots.  Them being hot seems to
> correlate positively with it being closer to working.

 The other chip is the FPU.  Both spec'd at below 3W max according to 
Siemens datasheets (no power dissipation directly given, but P = 5.25V * 
550mA at 12.5MHz); other vendors such as LSI or Performance Semiconductor 
quote lower figures.  I think them getting hottish isn't unexpected.

 There are 4 R2020 write buffers too complementing the R2000A and R2010A 
chips for the complete processing unit.

  Maciej