This reminds me of the entry in Dr Dobbs Magazine in the late 70s (probably) that when Mr Punch (Punch was a Satire type magazine of the same period) was asked for his advice on writing a C-compiler. "Don't".

Gary - thanks for the code! I checked it and it looks exactly how it should look like - simple, short, clean and self explanatory. Very nice!

Ahhhhh. Takes me right back to my operating systems class at university in 1985. The entire semester was spent building “Minix”. Less than 10 years later I start hearing about Linus and still don’t understand “why him”...???

Great video, Gary!! I had no idea anyone could pull this off with a little microcontroller!!

Amazing deep dive! Thanks so much Gary!

Yep, I'm happy that I found some of the ideas I've thinking of to call sequence of functions to run in multitasking system. But I couldn't call the functions directly, so I thought of taking the address of each function and call that function by address in the multitasking manager. And manager the to_run_task and queue_task by locks.

Congrats for 200K SUBS !!

Gary - Thanks for motivating me to read the ARM documents! I wrote this for M68010's in the 80's and it is just what I wanted for my Pico projects. BTW, I think you may want to run thread mode as privileged: it fixes USB Stdio and maybe more...

This is fantastic. I can't thank you enough for this wonderful video and excellent OS.

Random thing about C. I never knew you could put the typedef _after_ the struct (as in struct { ... } typedef mytype; as opposed to typedef struct { ... } mytype; )

Thank you. Phenomenal job

You wrote this? Impressed. I can recall a conversation we had in DMs when you asked me why I was asking all sorts of bizarre questions about the Raspberry Pi and I explained it was "What about people who want to write their own OS?". I can't help but wonder if that exchange lit the spark which led to this video? :)

Thank you for this.

Nice work!

Very nice. If you continue development it would be great to have a function that allows you to permanently end a task...

Great video Gary. I'm really looking forward to getting this going. I'm using vscode on windows. When compiling I get the following error: [build] D:\Dev\Pico\c-projects\piccolo_os_v1\context_switch.s:163: Error: SVC is not permitted on this architecture Is that an issue with the toolchain I'm using? Any suggestions for vscode on windows environment? Thanks !!

*GARY!!!* Good night Professor! Good night fellow classmates! Stay safe out there!

Btw, side question - what font is that?

Gary, have you ever looked into Forth Programing Language? It is older than C.

A very interesting project Gary. Thank you. Have you considered a version of Piccolo to run on the rest of the Raspberry Pi range? I have several of them, with the Pi4 as my test machine, and no need for a Pico. But I would like to go through the process of learning and building a simple OS. Yes, I know that there are several Linux distros that allow you to roll-your-own. But by the time you get to even a small modern Linux, things are very complex for a beginner. Also, Piccolo could well become the next Minix, and so find a place in most universities.

I wish you were my University Teacher! 👍👍

thanks for the hint... after this video... I'm already writin' the PicolloWUM--- a fantastic OS... will run on R-PI Zero,,, and can use any Windows/Unix/Mac program... (PS: don't wait for me... this can take a while...) ;-))

Did you ever get a V2 (pre-emptive OS) off the ground? FWIW the AtariST MiNT Kernel is also cooperative multitasking

Interesting...personally, I would use a multitasking version of FORTH, but hey, RPN rocks. :-)

A newbie question: In the collaborative model described, what happens if a process never calls piccolo_yield? Because it dies for some reason? Does that mean we have a zombie process, whose very existence means it never yields control and the whole shebang crashes?

So you are requiring the task to give back control occasionally to the OS handler? Is there a timer interrupt for the Pi that you could use to force threads to give up their time slot for the next in the list? It seems simple enough to make it multi-core functionality.

Hi Gary, I am very impressed with the depth of your videos this is very unusual for UKposts. I have been playing with the code on your repo. when making your piccolo project I get an error with the assembler around the use of the instruction SVC #0x00 . I know that the SCV instructions is optionally implemented in some of the Cortex-M0+ (synthesis option) consequently the arm_none_eabi_gcc has to target options one including the SVC instruction: -march=armv6s-m and one without it: -march=armv6-m. As far as I can see the makefile uses -march=armv6-m by default thereby causing the fault: "context_switch.s:163: Error: SVC is not permitted on this architecture". Are you using specific cmake arguments used to overwrite this?

Does anybody have link to a video or photo's of this OS in action on the Pico? Before I delve into C and understanding how to get this working etc. Can you use a keyboard for input? Or only human input via UART?

Haven't got the Pico yet so I can't experiment yet, but how do you use both CPUs?

Favourite drink: JD. Not sure it's a good idea to drink and code though.

Wild Turkey and Cola in the left hand, Coopers Red (Australia) in the right hand, ready to go.

This is what going hardcore looks like

Isn"t this basically how one would handle ISR's in x86 assembly?

Hi Garry, the RPI Pico is now on supported on Platform IO, check out github.com/Wiz-IO/wizio-pico The flashing LED sketch works with the only requirement is to fit a reset switch to the board.

Kamiccolo -Goku

Y preventivo?

Why is this video not in 1440P 😔

Will there be speed test g between Rog Phone 5 and IPhone 12 ?

Haven't clicked this fast 🤣. 1 minute ago

Why not "PiccolOS"...?

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Omg 🤐

DBZ fan?

I haven't watched this yet, but if I haven't written the Windows 11 by morning after watching this I am unsubscribing.