[RantyDave]

Phones, not TV's, but that's pretty much the idea. Even better, the ARM core was tacked on as a sort of "dammit, I supposed we'll have to run applications" kinda thing and isn't even necessarily initialised during boot.

Raspberry Pi's actually boot on a really fringe processor called a VideoCore. Arguably the GPU bootstraps the CPU, which makes my brain hurt.

[swiftcoder]

This sort of thing is not uncommon in the embedded space. Lots of devices basically built on a DSP with a tiny arm core tacked on the handle application logic

[rbanffy]

> Lots of devices basically built on a DSP

There were many X terminals running off nothing but a Texas 34010, which was a very DSP-like CPU that ended up in a lot of high-end graphics acceleration boards for PCs and Macs (and Unix workstations).

The fact it could boot up an X server is quite extraordinary.

I wonder what the VideoCore looks like to the programmer.

[kjs3]

The fact it could boot up an X server is quite extraordinary.

Since it was designed explicitly to serve that purpose, I'm not sure why it's 'extraordinary'.

Disclaimer: I spent time at a 34010 X terminal shop.

[rbanffy]

> Since it was designed explicitly to serve that purpose,

I never imagined that. Now I'm surprised there were no desktop computers based on it. I knew the Intel 860 and 960 were designed as computers and got some usage as that, but I never knew the 34010 and 34020 were like that.

[devmor]

Sidebar but it’s very annoying how it now takes me a moment to think if people are talking about a social media website or an open source graphical server when I see “X” being discussed in a tech context.

[brianshaler]

With rare exceptions, the social media website tends to be referred to as "X formerly Twitter" or just "Twitter" for short

[rbanffy]

Just call it Twitter. Let's deny Elon the pleasure ;-)

[phendrenad2]

I guess technically a CPU core within the GPU ASIC block loads code into the main CPU. What a weird design. Feels like the kinda of things that Wozniak would come up with to shave cost from the Apple Macintosh.

[djmips]

AFAIK Woz only really worked on Apple II and Apple /// but his Apple II disk drive controller lived on and was included in the Mac.

[Findecanor]

Woz also designed Apple Desktop Bus for keyboards and mice. First used on the Apple IIGS, and then on Macs from Macintosh II onwards up until it was replaced by USB.

[namibj]

Ehhh, video core is basically just a (iirc multi-core/-thread) vector processor. Funnily enough, this also makes these rather cheap number crunching hard real time chips with the high-bandwidth IO (for hard-real-time) of a Pi. Notably, it's camera/display interfaces.

[codedokode]

Could it be a protection of IP? This way program on main CPU cannot access initialization code and the user cannot learn how to do it.

[dezgeg]

Doesn't really help when the VC firmware is loaded from the SD card anyways

[ajb]

Are you sure about that? As I understand it, the other product that chip was used in was a Roku stick.

It's true that videocore was intended to be a GPU for phones, though.

[Crosseye_Jack]

I am only going off my memory, so I could be mistaken. But IIRC the OG pi used processors originally designed for phones (at least the one that hit the market, eraly prototypes were based on Atmel micros), The iPhone used a processor originally designed for a set-top box from Samsung which was then underclocked to save on battery.

IIRC they realised that the micros were not going to cut it, they went to Broadcom (Which Eben was working for at the time) and they were able to supply some "overstock processors" for cheap, which became the processor used in the Pi. Remember at the time the Pi was never designed to be for "makers" but to be a cheap computer to help better kickstart education, it was never designed for "us", but we all said "hey, cheap little linux computer, I'll take 5!

[ajb]

It could be the both things are true, it's common enough for chips to be made to serve two markets to save capital cost

I've come across some (unknown provenance) information that bcm2763, which was advertised as a phone chip on an old version of the broadcom website (via archive. org) was the same die as bcm2835, but with dram hooked up in a different way.

[secondcoming]

I remember a Nokia device that used Videocore, I not sure if it ever made it to market.

[throwaway67743]

Iirc the original pi was a set top box chip, because it still at the time had directfb gpl code available (as every StB used) - I remember it quite distinctly as I laughed how pointless their experiment was (sort of wrong, but actually the rpi has done more for encouraging competition than anything they've produced themselves)

Also broadcom haven't made phones, while they do still have a strong tv/StB market share, but that's declining due to their incessant proprietary attitude

[numpad0]

I suspect it's less about having CPU as afterthought, than about how and who is to take CPU out of "awaiting to be booted" state. Ancient CPU simply had a BIOS mask ROM hardwired to reset vector and immediately load from it upon release of reset line, nowadays and on more complex systems, I believe that's what Intel Management Engine/Apple Secure Enclave/VideoCore GPU/etc. will do, not the main CPU itself.

[ChrisRR]

Not strictly either/or. Just used in whatever people wanted to use it for.