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Comment by blueflow | Hacker News Reader

ARM is a microcontroller architecture.

If you look at two examples, they may have the same "architecture", but on one, more of the architectural blocks are on-chip, and on the other, less. I don't think what is on or off the chip really changes the architecture, though it would probably change the performance, and the pin boundaries do drive other system considerations. But otherwise, the architecture is the architecture, or am I looking at it wrong?

1) This is a distinction without a difference.

2) SRAM is almost always on the die, not external. Here's a die shot of a random STM32 (cortex M): [1]. The SRAM is quite obvious.

[1] https://s.zeptobars.com/GD32F103CBT6-Si-HD.jpg

It is a meaningful distinction. A microprocessor architecture would require support chips, like a south- and north bridge, plus RAM in additional chips.

x86 being the classic example. Here [1] is an example of a microprocessor board, you can see the MX support chips on both sides of the CPU. As you can see, the RAM (and the most of the address space-mapped things) is not on-chip. The bus is wired across the PCB.

[1] https://upload.wikimedia.org/wikipedia/commons/d/de/386DX40_...

Even x86 has on-die SRAM that can be used in boot. It's better known as L1, L2, and L3, but you can configure Intel's FSP to make it usable for boot code with the so-called cache-as-RAM feature. The technical details are different than e.g. ARM because it's cache rather than properly addressable memory, but the general idea is the same.

All the RAM you see on the motherboard is DRAM. It's a totally separate thing and happens to be what the FSP initializes after it loads stuff into SRAM.

These words are used interchangeably, you need to specify exactly. The main distinction is does it have a MMU or not.

"VPN" evolved to mean proxying service, now people are denying that my tinc setup is a VPN.

"Emulation" evolved to mean virtual machine, now people are denying that wine or xterm are emulators.

"Operating System" evolved to require virtual memory and paging, now people are denying that MS-DOS was an operating system.

"Microprocessor" evolved to mean computing chips with MMU, im waiting for people to deny that the 8086 was an microprocessor because it does not have an MMU.

The infinite shitcycle of people improvising language instead of researching.

Wine is not an emulator, it's a PE loader and a Win32 API for Unix. And XTerm is more like a terminal simulator.

Wine actually IS an emulator, just not the kind of emulator you think of. While wine is not an virtual machine, it literally emulates the win32 api.

https://web.archive.org/web/20150928042254/http://wiki.wineh...

I mentioned the shift of meaning to "virtual machine" in the post you replied to, please read it more carefully.

Emulation and Simulation are different in some regard: emulation is only imitating some aspect of a thing, while simulation imitates a thing by using (usually physical) models.

xterm is a VTxxx emulator, and VT simulator does look like this: https://www.pcjs.org/machines/dec/vt100/

I'd argue that wine is a bit of a stretch considering that we're on the third implemention of win32 in Microsoft land as well (DOS/win32s, Win95, NT/Win32k). At that point win32 is a concept already abstracted away from a specific implementation

I totally agree with your main point though that emulation is a broader topic than is generally thought.

Then Windows NT is emulating Win32.

Also, back in the day emulators emulated the CPU for sure, while an API implementation wasn't never called "emulation". Ever.

xterm calls itself an emulator in the manpage right now.

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