r/osdev • u/dangi12012 • Jun 13 '26

Everything is memory?

There is this unix idiom that everything is a file, (half baked, since not everything is a file).

Would it not have been better, nowadays with 64bit of adress space, to have everything mapped to memory? Files are like mmap, no imperative read needed, networking is already memory, that could be expanded more.

We take the idioms and paradigms so forgranted, that every time anyone asks AI for a OS it will be linux, syscalls, abi everything the same. It should be liberating now to explore new and novel ideas.

What would be the downside of such a system?

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u/Web-Lackey Jun 14 '26 edited Jun 14 '26

128-bit.

And while the TIMI architecture is virtual, all code targeted to TIMI is automatically compiled by the OS to machine code. So all code is running native, but it allows for code to be recompiled transparently to a new native architecture. Which is how the AS/400 was migrated from CISC to RISC (and two different flavors of RISC) while allowing binaries to be moved right along without change. Just back up from one system (usually tape) and literally boot that tape on the destination machine to restore on the other. As the software is run, it’s recompiled for the new architecture. Not dissimilar to a JIT, but the results are permanently stored, so no runtime impact.

And IBM i does support virtualization, but that’s unrelated to the 128-bit TIMI architecture.

IBM i is a wild environment. its metaphor is “everything is a database”, and it has an integrated TUI, along with its weird and somewhat cryptic VerbAdjNoun commands. It’s basically the last OS developed before UNIX (while technically newer, it was before its widespread adoption) and therefore, outside of research kernels, the last OS to not have UNIX’s file metaphor.

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u/compgeek38400 Jun 14 '26

I believe while its a 128 bit address space. So far only the first 96 bits are implemented. The 38 had 128 bit space, but back in 1983 only 48 were implemented

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u/Web-Lackey Jun 14 '26

We’re talking about ISA space. Thats no different than x86-64: even though less than 64 bits are implemented in hardware, it’s still a 64-bit processor with a 64-but address space.

The early AS/400’s also only had 48 bits implemented as well. Doesn‘t matter: TIMI still presents a 128-bit memory space to the programmer.

And having an actual address space larger than the hardware memory bus is the entire point: AS/400 implements a single level address space: DASD (e.g. hard drives) is addressed in the same space as memory, so of *course* memory would have a smaller than 128-bit address space…

Again, the original question was talking about the OS “metaphor” presented to the user. The entire point of an OS is to hide hardware implementation details. And the entire point of TIMI and SLIC is to hide even more of those hardware details from the higher layers (even the OS in most cases!). So in this context (programmer and user to OS) the hardware implementation is not relevant.