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A comment on How could the early Unix OS comprise so few lines of code?. Parent comment

Re:How could the early Unix OS comprise so few lines of code? by msla on Monday September 11, 2023 @06:53AM (#37465391)
Back then, fitting in RAM was a big problem: The PDP-11 (the first kind of computer to run Unix, as opposed to UNICS) had a 16-bit address space, which gives you 64 K of RAM if you ignore the fact peripherals were memory-mapped and so took addresses away from actual memory. Later models had split I+D, or separate address spaces for Instructions and Data, but that's still only 128 K.

https://gunkies.org/wiki/PDP-11_Memory_Management

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Re:How could the early Unix OS comprise so few lines of code? by shrubble on Monday September 11, 2023 @07:39AM (#37465771)
Later models could address 18 (256k) or 22 bits (4Mbytes) of memory.
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Re:How could the early Unix OS comprise so few lines of code? by systems_glitch on Monday September 11, 2023 @10:43AM (#37468018)
Still restricted to I+D of 128K mapped in at any given time, plus your 8K of I/O space for bank 7.
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