A closeup of the 8086's microcode ROM. The pattern of doped silicon is visible. This creates the transistors that hold the ROM's contents.

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1. Ken Shirriff (kenshirriff@oldbytes.space)'s status on Sunday, 15-Jan-2023 04:12:47 JST Ken Shirriff

   in reply to

   A ROM (read-only memory) typically stores 1's and 0's by the presence or absence of a transistor for each bit. So the more 1's you have, the more transistors. It's inconvenient for the transistor count to change with the data, so "transistor sites" are usually counted.
   This image shows a closeup of the 8086's microcode ROM. It is arranged as a uniform grid. The regions of doped silicon form transistors (or not).