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Linux on an 8-bit micro (2012)

dmitry.gr

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Re: Linux on an 8-bit micro (2012)

#41

Post by [deleted] »

revelation wrote: post #37
duaneb wrote: post #34

Earlier quoted context omitted.

Of those, it seems like only TinyOS would qualify (a full userland stack that you can develop from) under the same qualifications that netbsd might qualify.... To be clear, by "true os", I mean a posix runtime, preemptive multitasking with threads and processes, memory protection. Still, cool links (I'll save that TinyOS for later this week), and I like the username.

Most 8 bit micros don't have an MMU, so you can't have memory protection or virtual memory. That's a hardware limitation.

[deleted]

Re: Linux on an 8-bit micro (2012)

#42

Post by reidrac »

duaneb wrote: post #7

This is probably one of the crazier projects I've ever seen. I've often contemplated what running a "true os" on an 8 bit CPU would entail, and TBH the idea of an emulator never struck me. On top of that, a hand-wired linux computer with hand-written arm emulator? Ridiculous.

I'm not an expert but AFAIK it makes sense: he's using an AVR and that's Harvard architecture, meaning code and data use different buses so all you can run must be in the flash of the microprocessor.

So emulation is a way to workaround that "limitation".

Edit: on mobile, typos

Re: Linux on an 8-bit micro (2012)

#43

Post by duskwuff »

cnvogel wrote: post #23
logicallee wrote: post #16

Does anyone know why these 8-bit processors are so expensive? The two he listed ATmega1284p and ATmega644a cost like $9.07 (qty 1) to $4.88 (qty 2.5k), and $7.08 (qty 1) to $3.79 (qty 2.5k) on Mouser. I would have thought we're talking like a $1.30 chip. Meanwhile look at what you get for $6 - http://linuxgizmos.com/quad-core-allwinner-soc-targets-low-c... Am I missing something? Or are his 8-bit microcontrollers act…

The ATMega128... parts are the second-to-largest 8-bit micro that Atmel sells, I think they already have a strange combination of a lot of flash & RAM (for a 8-bit CPU), but not that many, or that complex, peripherals. So they might only be used in (comparatively) low volume in fringe applications. As an example for "embedded, non Linux" microcontrollers, the lpc1227 (32bit Cortex-M0 @ 45MHz, 128k Flash) is only half…

The part the author is using here is especially odd: it's on the large side for AVR microcontrollers (128 KB flash, 16 KB SRAM), and comes in a DIP package. That's an unusual combination; most microcontrollers that size nowadays are ARM, and are often only available as surface-mount parts.

Re: Linux on an 8-bit micro (2012)

#44

Post by myrandomcomment »

duaneb wrote: post #38
myrandomcomment wrote: post #33

Earlier quoted context omitted.

I am not talking about Contiki running on this platform. If your read the story you will see the author wrote an ARM emulator to run on the CPU to the. Run the code. I was staying it would be more interesting if it was native and using Contiki as an example that you can run on an 8 bit Cpu without and MMU.

Well, you can run many things without an MMU, the question is whether it will be at all pleasant to use without an MMU. What makes linux nice is not the fact that it allows you to run code, but it allows you to run thousands of pieces of code at once, stably.

That also worked just fine on Amiga OS 3.1 without and MMU :)

Re: Linux on an 8-bit micro (2012)

#45

Post by [deleted] »

Zardoz84 wrote: post #30
dalke wrote: post #28

Earlier quoted context omitted.

Oops! Yes. 16 bit. I was thinking of the 8 bit data bus of the 16 bit 8088. What about Micronix? http://www.retrotechnology.com/herbs_stuff/mnix_micronix.htm... - "As far as I know, Micronix was the only Unix-like multiuser system ever to run on an 8 bit processor."

FUZIX and UZIX runs on an Z80

[deleted]

Re: Linux on an 8-bit micro (2012)

#47

Post by pantalaimon »

duaneb wrote: post #34
pantalaimon wrote: post #32

Earlier quoted context omitted.

What about RIOT [1], Contiki [2] or TinyOS [3]? [1] http://riot-os.de/ [2] http://www.contiki-os.org/ [3] http://www.tinyos.net/

Of those, it seems like only TinyOS would qualify (a full userland stack that you can develop from) under the same qualifications that netbsd might qualify.... To be clear, by "true os", I mean a posix runtime, preemptive multitasking with threads and processes, memory protection. Still, cool links (I'll save that TinyOS for later this week), and I like the username.

I think you will like NuttX [1] even more :)

[1] http://www.nuttx.org/

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