3 ms·
Ah, memories. I was a manufacturing engineer in a bipolar factory from 1989 to 1992, and BiCMOS was the perennial hope for a future for our acquired skills. W
by rossdavidh 2y ago
Ah, memories. I was a manufacturing engineer in a bipolar factory from 1989 to 1992, and BiCMOS was the perennial hope for a future for our acquired skills. When word broke that the Pentium would have one, it seemed significant. On the whole, though, it didn't have the impact that was hoped for; bipolar hangs on (like COBOL) in certain niches, but I think despite the theoretical advantages, the disadvantages of having to think about both bipolar and CMOS transistors in the engineering, was too much of a price to pay.
Lesser known reasons: as bipolar transistors went to polysilicon gates (which have a tiny, ~1-2 Angstrom thick layer of oxide in them) and MOS transistors started to become leakier through their ever-shrinking gate oxides, the distinction between MOS and bipolar transistors became fuzzier. Modern MOS transistors leak less current through their gate oxides than the bipolar transistors did through the polysilicon emitter, but the physics of the two is not as different as it was twenty years ago.
- FuriouslyAdrift 2y agoI remember the Exponential Technologies bipolar PowerPC chip running at 533 MHz back in 1997... so sad Apple killed it https://web.archive.org/web/19970712065424/http://www.byte.com/art/9612/sec11/art1.htm https://web.archive.org/web/19970712065424/http://www.byte.c...
- kens 2y agoThat's an interesting chip. You don't see many bipolar processors. (The Pentium has a few bipolar transistors sprinkled around, but it's mostly CMOS.)
- formerly_proven 2y agoDEC made a one-off ECL CPU in 1993: https://bitsavers.org/pdf/dec/tech_reports/WRL-93-8.pdf https://bitsavers.org/pdf/dec/tech_reports/WRL-93-8.pdf 300 MHz / 115 W. Ten years later, you'd have Pentium 4 at 3000 MHz and 115 W.
- chasil 2y agoThe VAX 9000 was also an ECL implementation. https://en.m.wikipedia.org/wiki/VAX_9000 https://en.m.wikipedia.org/wiki/VAX_9000 It was an enormously expensive failure.
- deleted 2y ago[deleted]