VAX9000 unearthed

[Chuck Guzis]

On 2/20/22 10:10, Mark Kahrs via cctalk wrote:
> I heard Butler Lampson once exclaim that ECL design was in some ways easier
> than TTL.  If you terminated every line, you get controlled impedances with
> controlled edges.  This was the design philosophy for the Dorado.

Indeed--ECL WW prototype boards usually had a 3rd row for SIP
termination resistors alongside the DIP sockets.  One nice thing about
ECL is that there are many fewer problems with power rail spikes.  On
the other hand, the constant power consumption needs beefier power supplies.

I recall that Honeywell redid one of their mainframe designs in ECL,
with somewhat disappointing performance results.  I don't recall the
details offhand.

--Chuck