Gregory's ServerThe original Pentium chip was introduced in 1993. It was the first "superscalar" x86 chip, able to run two instructions per clock cycle. I took this die photo of the chip yesterday. The chip has three metal layers; the thick lines you see are the top metal layer, mostly power and ground. The silicon itself is almost entirely obscured. Around the edges of the chip, tiny bond wires connect to the bond pads, providing the connections to the chip's external pins. 1/N
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Here's a closeup of the die showing the Pentium Processor name and the Intel copyright. The M-in-a-circle is a Mask Work symbol, like a copyright but for IC masks. I convinced the Unicode Consortium to add the symbol to Unicode, but I don't think any fonts support it yet: 🆭
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@thomasmey As Wikipedia says, the presence of the copyright symbol "continues to affect remedies available to a copyright holder whose work is infringed." The Pentium die has a lot of initials from the designers, in various shapes and sizes. These photos show a subset of the initials. Intel removed the initials from the next revision (80502).  @kenshirriff The Bus Interface Logic block seems shockingly large, half the area of either cache. What's going on? @tommythorn In comparison, on the 8086, the Bus Interface Unit is roughly half the chip. The Bus Interface is doing a lot: performing prefetches, handling memory and I/O bus cycles, handling interrupts, bus hold, bus locking, cache operations, and so forth.  @kenshirriff TIL Zaphod Beeblebrox was a chip designer. Explains why he went on to put his initials onto his own brain.   Ken, do you recall what the dimensions are of this label? I suspect the vertical lines are an indication of something but I don't know of what. @IAmDannyBoling The vertical lines are columns of 5 tiny dots, vias from the power and ground rails to the metal layer below. Right. But what are the dimensions of the label itself? I'd love to know just how tiny that label must be. @IAmDannyBoling The label is pretty big by IC standards: the rectangle holding the text is 1.1 by 0.2 mm. That's even smaller than I thought it would be. Thank you so much for your entertaining and very inform posts, Ken. @kenshirriff I think I remember that the oroginal Pentium was still a 5V chip. If correct, that would explain a good deal of its power consumption. @kenshirriff I can't help but compare this to ENIAC, and ESDAC, where the clock was how all the parts worked together to produce the result. The idea of turning it off to some parts of the machine is a crazy leap of invention. (Of course, in ENIAC, if you didn't need parts of the machine, you just jumpered around them. I think they still consumed mass quantities of power, though.)   @kenshirriff I have a lot of affection for the Pentium. The first 64-bit (-data-bus) x86 CPU. 😌 |
The original Pentium was power-hungry, so Intel soon released an updated version that could turn off the clock to parts that weren't being used, saving power. The original (P5 architecture, part number 80501) on the left has a noticeably larger die and package than the update (P54C, 80502). The original was built with Intel'ss 800 nm BiCMOS process, while the update was 600 nm.