The OG IBM PC could address up to 1MiB of memory, which seems laughable now, but was a huge amount in 1981. However, that address space was split between user accessible RAM (640KiB) and that used for video, BIOS, and peripherals (384KiB).
That 640KiB number is interesting. Chances are you have run across a quote attributed to Bill Gates where he says 640K is all the memory anyone would ever need. This supposedly happened in 1981, but the reality is that Gates probably never said it.
This quote seems to be one of those things that lives on the internet and is given credence because it has been around for so long. You can verify it against a mountain of attributions that are all verified against another mountain of them. But there is no actual original quote.
I suspect there was some mention from Microsoft, and possibly Gates, when discussing DOS on the IBM PC where they referenced how great having 640K was going to be. At the time, that was a big deal. Somewhere, that got twisted into the quote, and once something is on the internet…
Our picture today is a close-up of two 8 gig sticks, which, amazingly, is not a whole lot of memory now.
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