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Ken Shirriff

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
30 Nov 2023 at 16:55 | Open on oldbytes.space
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Ken Shirriff

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
30 Nov 2023 at 16:55 | Open on oldbytes.space
Ken Shirriff

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
30 Nov 2023 at 16:55 | Open on oldbytes.space
Alolan Yoda

@kenshirriff I have a sort of weird question. Are all industrially fabricated chips this dirty? In this image, for instance, you can see a lot of defects in the metallic regions, even in the transistors area. I work in a small lab with a cleanroom and I fabricate small chips for biological applications. I never had to do anything at an industrial level, as I mostly do research on new types of chips. But we use mostly the same technology used in CMOS fabrication, and if my chips had this amount of defects I would not be confident in their performance. Is it a question of the metal you used? I have used AlSiCu (mostly aluminum with some Cu and Si for enhanced conductive properties), and when dry etching we noticed some defects that could be considered similar to this.

@kenshirriff I have a sort of weird question. Are all industrially fabricated chips this dirty? In this image, for instance, you can see a lot of defects in the metallic regions, even in the transistors area. I work in a small lab with a cleanroom and I fabricate small chips for biological applications. I never had to do anything at an industrial level, as I mostly do research on new types of chips. But we use mostly the same technology used in CMOS fabrication, and if my chips had this amount of...

1 Dec 2023 at 14:03 | Open on universeodon.com
Ken Shirriff

@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.

6 Dec 2023 at 17:18 | Open on oldbytes.space
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