Gregory's ServerHere's the circuitry for the mask register. Three input lines select how many bits for the mask, decoded by a bunch of gates. 11/14
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 Also my previous tweets on the Intel 82586: A bonus photo of the 82586 die with the metal layer removed, showing the underlying circuitry. I stopped dissolving the oxide layer a bit too soon, so it's a bit ugly. There are some random colored areas due to thin-film interference. The bond wires are around the edges. 14/14  Have you come across any errata where the 82586 ring handling has a bug and the part goes deaf until you reset it? I know it had a bug like that but now I cant find the errata for the part. @bitsavers Robert Garner is trying to track down the errata sheet for the 82586; he might know more. |
So that's how exponential backoff was implemented on the Intel 82586 Ethernet chip.
For more, see my blog post:
https://www.righto.com/2023/10/reverse-engineering-ethernet-backoff-on.html 12/14