Gregory's ServerThe 386 processor (1985) was pivotal for Intel, moving the x86 architecture to 32 bits and moving the design to CMOS. Everything in the processor is controlled by the clock. Some tricky circuitry on the chip (red) generates the clock; let's take a look inside the die... 1/11
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The 386, though, used CMOS technology (like modern processors). As a result, it needed active-high clocks for the NMOS transistors and active-low clocks for the PMOS transistors, four clocks in total. Complicated on-chip circuitry generated these clocks. 3/11 First, the 386's clock pad received an external clock signal at twice the desired frequency. Two transistors were connected as diodes to clamp the signal if it was too high or too low, protecting the chip. 4/11 @AlolanYoda Some of it is debris from when I opened the chip. But I usually see some spots on the metal. I don't know if these are defects or just harmless irregularities that show up under the microscope. @kenshirriff I found your account through your blog post and I'm very happy to have found it. Great write-up, super interesting. Thank you for taking the time to write this! |
Early microprocessors such as the 8080 used a two-phase clock: when one phase is high, the other is low, with a gap between the high part of each phase. Processing moves step-by-step through the circuitry, one phase at a time. 2/11