Pipelining and Dec Jupiter thoughts....

Paul Koning paulkoning at comcast.net
Fri May 7 11:29:29 CDT 2021

> On May 7, 2021, at 11:45 AM, Jon Elson <elson at pico-systems.com> wrote:
> On 05/07/2021 07:10 AM, Paul Koning via cctalk wrote:
>> They built an interesting hybrid system where you could write the design partly as geometries (for things like memory cells), partly as transistors, partly as gates, and partly as C code. I remember an example, where they had a transistor schematic for a single-bit latch, and then wrapped it in a loop: "for (i=0; i < 64; i++) { <schematic> }". The magic was that (apart from the few bits of explicit geometry-level design) it was all parameterized, so they could regenerate the actual wafer geometry overnight for a new fab. 
> That sounds a lot like VHDL, which can be used to synthesize chip layout.

It's a bit different.  In VHDL you can do gate level or behavioral modeling, but the idea of wrapping a picture in a "for" loop was something I haven't seen anywhere else.

Also, this was 30 years ago, roughly, when chip design technology was a whole lot more limited.

>> Another part of the puzzle was figuring out how to feed 100 watts of power to a chip, and get rid of that amount of heat, neither of which were anywhere close to what was done at the time. I still have some of the tech reports that describe that piece (and I contributed a wild idea -- which unfortunately DEC didn't get around to patenting before the project was shut down). paul 
> IBM was tinkering with high density ECL system construction from 1965 or so, as a follow-on to the System 360.  They had several aborted projects, FS (Future System) and ACS (Advanced Computer System) that were very advanced supercomputers.  The technology eventually came out as the
> 309x series, with several hundred MSI ECL chips on a ceramic interconnect substrate, water-cooled
> with a big plate with copper "nails" that pressed down on the back of the ICs.  That was the 308x system, introduced in 1984.

The packaging work DEC did included building a heat pipe package that could handle well over 100 watts with air cooling, and also an investigation of the current carrying limits of chip bond wires.  It turned out gold wires have really good properties: they handle a whole lot of current and they have a very clear upper limit; stay even a little below that limit and the wires last basically forever.


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