<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 2015, Oct 2, at 11:42 AM, John Hearns <<a href="mailto:John.Hearns@xma.co.uk" class="">John.Hearns@xma.co.uk</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="http://www.theregister.co.uk/2015/10/02/seymour_cray_90_anniversary/" style="color: rgb(149, 79, 114); text-decoration: underline;" class="">http://www.theregister.co.uk/2015/10/02/seymour_cray_90_anniversary/</a><o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><o:p class=""> </o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><o:p class=""> </o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">I remember learning about Gallium Arsenide and Emitter Coupled Logic when I was but a little graduate student.<o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">I don’t suppose anyone else will remember what FASTBUS was – but it was fast because it used ECL!<o:p class=""></o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><o:p class=""> </o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><o:p class=""> </o:p></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><o:p class=""> </o:p></div></div></blockquote></div><br class=""><div class="">The good old days! I heard Seymour Cray speak at Stanford in the late 70’s I suppose. Later at Digital</div><div class="">I got a chance to design with ECL for part of the first Alpha machine. The Alpha EV3 and EV4 chips had truly weird IO pads, and could speak either TTL or ECL on the outside. For the Alpha Demonstration Unit we chose 100K ECL because power and cost were not that important. As the Register article notes, ECL has just beautiful signaling properties. If you followed the transmission line rules exactly there just weren’t noise problems. And fast! That project is when I first had to consider picoseconds. The jellybean gates we used were about 200-300 pS.</div><div class=""><br class=""></div><div class="">The stuff did suck power though. IIRC we had 4-0 welding cable to connect the power supplies (400 Amp at -4.5 V?)</div><div class="">to the chassis. The welding shop that fabricated the cables asked “what sort of welder uses 18 inch cables?</div><div class=""><br class=""></div><div class="">The other point the article makes is that Cray designed simple machines and back then more logic meant longer wires, which were slower. So a simple machine was a fast machine.</div><div class=""><br class=""></div><div class="">In recent computers logic is basically free, but the resultant complexity of hardware and software is not so good.</div><div class=""><br class=""></div><div class="">-Larry</div><div class=""><br class=""></div></body></html>