Repair methods (was Cromemco 3101/Beehive B150 score)

[Don Y]

William Donzelli wrote:
>> I worked on a 100MHz (doesn't sound like much, 30 years later :> )
>> CPU in the mid 70's.
> 
> Damn impressive for the 1970s. What CPU? 

It was a custom device.  I.e. the CPU was fabricated entirely
of discrete ECL chips.  The size of a medium sized briefcase.

>>  The problems I found were all the *different*
>> ECL families (10K, 100K, MECL III, etc.) plus all the other
>> cruft to interface the real world to them (4000 series CMOS
>> for the JTAG stuff, other level translators for the "fast"
>> stuff).
> 
> 10K sucked. MECL III sucked. 100K was the way to go, except for the
> relatively skimpy selection. And never mix...

But you couldn't get "everything" in any given family.
Hence the problems...

>>  And, the colossal *power* requirements (>500W for
>> that CPU alone!).
> 
> Real computers used real power supplies.

Yeah, I always enjoyed "adjusting" the -Vbb supply -- a
*shunt* regulator fabricated with a whopping big Lambda
power supply driving *BIG* diodes to ground... "select
at test".  <shrug>  Crude but it *worked*!  Power supplies
that big can't descriminate between their load and a dead
short!  :-(