raspberrypi

This is going to end up somewhat specific, as most low-level initialization routines are. ARM vs x86 vs RISC-V vs MIPS vs a BASIC stamp or propeller etc... I will suggest studying some general Assembly language concepts, memory locations, how to set-up RAM timings and bring offchip RAM into an address space, etc. This stuff is used daily in the world of microcontrollers, I'm a huge fan of the Parallax propeller, in which the Spin interpreter in ROM launches Assembly routines on individual cores in about the simplest fashion possible... Some things you may find interesting: https://github.com/dwelch67/raspberrypi https://github.com/rsta2/circle https://ultibo.org/ Think of the latter 2 as "HAL plus some primitives" rather than RTOS...

The Application Server is in progress, but it builds. The problem is that on x86, you can fall back on the BIOS w/ VESA to display video; while ARM lacks that functionality. If you can find/build a video driver it should Just Work(tm). You can see the current video drivers here: https://github.com/haiku/haiku/blob/master/build/jam/images/... Which are all x86/amd64-based. The RPi would actually be relatively simple to throw a framebuffer video driver together for, though: * https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/s... * https://github.com/raspberrypi/firmware/wiki * https://github.com/dwelch67/raspberrypi/tree/master/video01

And these operating systems in both Smalltalk and Lisp were both better and easier to write than the standard ones of today. Look, I love Lisp as much as the next hacker, but is Alan Kay for real? Where's the Lisp equivalent to this C code? https://github.com/dwelch67/raspberrypi/tree/master/blinker0... More importantly, where's the accompanying toolchain? Seriously, I really want to know because I'd love, Love, LOVE to play around with it.

For what it's worth, you can code bare metal on the Raspberry Pi as well. It just doesn't have the community and support that Arduino currently has. https://github.com/dwelch67/raspberrypi

The ARM core on the Raspberry Pi is accessible via JTAG. It requires a board with an FT4232H or FT2232H chip. See https://github.com/dwelch67/raspberrypi/tree/master/armjtag for details.

Even if you just want one platform, there is a lot of machinery you need even to boot up, load something from disk, access a USB keyboard and mouse, and display some text. ACPI and UEFI add considerably to this. Then there's bugs and debugging. If you have a bug in your disk driver you can slowly lose data without noticing. Quite a lot of other bugs will lock your system and you need to debug painfully from whatever logs you can find. Building in a non-C language might make this a bit easier but won't save you from the hardware locking up. Once you've done this, what have you gained? You have an OS with no userland and no applications. What bits of Linux/BSD do you actually want to replace with something else? The code is fairly modular and OSKit exists to help with this. The nearest to what you describe is probably retrocomputing; people

Another fantastic resource: https://github.com/dwelch67/raspberrypi

> The raspberry pi is a much more complex machine than the arduino. 32 bit instructions vs 8 bit, 700MHz vs 20MHz clock frequency, GPU vs no GPU, 512MB memory vs less than 1MB I have no arduino experience and am happy to be educated, but I don't see how any of those things makes the pi harder to program. Maybe the instruction set's harder, but that only matters if you're writing asm. There's more stuff you can do, but that doesn't get in the way if you just want to code arduino-like stuff. > You certainly can make LEDs blink with a raspberry pi with your own non-OS code, but the difference in the amount of code required vs doing it in an arduino is pretty substantial. Here is some baremetal code that blinks LEDs on a pi: https://github.com/dwelch67/raspberrypi/blob/master/blinker0... It's not that bad, really. Admittedly some of the perip

> A Raspberry Pi is a fully functional computer so you have to wait for it to boot in to linux before it can do any other tasks. There's nothing to stop you programming the pi bare metal style like an arduino. It's not as well documented but it's perfectly doable and quite fun. https://github.com/dwelch67/raspberrypi http://www.raspberrypi.org/phpBB3/viewforum.php?f=72