Why do I "install" an OS on my laptop but "flash" a ROM on my phone?

Factual Questions
1

They’re both just computers, right? I understand that phone OSes are stripped down versions with only the drivers they need, tailored to a specific version of a specific vendor’s hardware. But is there a reason I can’t run a general purpose OS installer on my phone instead? What about vice versa? Can I create a flashable ROM for my specific laptop hardware configuration?

I think I have a general idea of how things got this way, and that the answer to my question is “that’s how things ended up, for historical marketing reasons”. Can anyone give more detail though? Why did it end up this way? What is in store for the future? Laptop ROMs? Generic USB Linux installers for phones? Some third thing?

2

I’ve started writing this response four times and kept stopping to go back and erase. I thought this was going to be very simple, but the more thought I gave it, I find that I’m as puzzled as you.

“Because it’s always been this way” is probably correct. The differences between PCs and phones 20 years ago was very stark. PCs had rewritable magnetic disks, and were expected to update frequently. Phones had burned in ROM chips, and were static for the life of the phone. Over time, as SSds came into PCs, and the concept of a remotely updatable OS for phones became the norm, they have converged with each other. The MS Surface represents a near convergence point, where something with a form factor of a large phone is running a full installation of Windows, and a Surface phone is probably only a couple years away at most.

Inertia is a strong thing in computer terminology. Look at the icons for print/save/dial and how little resemblance they bear to the operation that actually take place now!

3

Because your phone runs apps but your computer runs software.

4

The “ROM” in a phone which holds the OS is actually PROM. Which is to say a device whose bits can’t be re-written to individually, as can be done on a disk or RAM. Instead the entire thing has to be erased all at once and then completely re-written from end to end.

And the engineering term for that *clear all & rewrite *process is “flash”. And has been since PROM was invented in the 1970s. Some early PROMS were erased by physically exposing the silicon to a bright flash of ultraviolet light which fried all the trapped electrons out of the cells holding "1"s, so they all became "0"s. That erased the whole thing in a flash, then the new data could be written into the newly-blank device.

The ROM in a PC that stores the BIOS is also really a PROM. Which is why you “flash” the BIOS of a PC to update it.
Now in a PC the OS is a big bunch of software. With lots of configurable options chosen during set-up. And which parts of the overall OS code actually ends up on the hard drive depends on those options and on your particular hardware configuration.

The term “install” was chosen for the process of configuring and transferring software, OS or otherwise, from the distribution media to the PC’s permanent storage, typically a disk drive or SSD equivalent. And this term came in turn from the same practice used on minicomputers before PCs, and mainframe computers before minis.

So at the end of the day, we have the phone and tablet terminology bubbling up from the underlying hardware, through the hardware-abstraction-level software, and the OS-level software, and the installation control software all the way to the UI & marketing level.

Whereas in the PC (or Mac) case the terminology comes from higher in the stack. It starts at the OS-level software, bubbling up through the same higher levels: installation control software, UI, & marketing level.
And that’s what’s really going on. *Why *is it that way? Essentially arbitrary accidents of history.

When phones started out, they were pretty dumb devices not intended to be updated during their life. As they slowly morphed from single-purpose devices implemented in fixed-software-on-hardware to full up PCs in your hand, some terminology has remained rooted in their origins and other terminology has kept up with the changes.
We really ought to stop calling these devices smart-phones, because voice telephony is one of their least important and least complicated functions. They’re handheld computers. My vote for the new term is “tracker”, as in the device everyone and his Big Brother use to track me. And you.

5

OK, I seriously need a cite for this.

All the EPROMs I’ve ever worked with took many minutes to erase. The UV erasers were marketed by how much power they could deliver, and even the biggest still took over a minute.

As I remember it, Flash memory was named because an entire page of memory could be wiped in mS (in a “flash”), as opposed to EPROM where the entire chip had to be erased (slowly). There were also competing technologies such as EEPROM and NVRAM which still occupy niches.

6

Besides coming from a curated app store and probably all being written in the same, vendor-approved programming language, apps are the same thing as “software”. My phone’s OS is a heavily modified form of Linux. Whatever differences there used to be between phones and PCs mostly aren’t there anymore, hence my question. My phone boots from an internal SSD just like my laptop. Besides the ridiculously constrained power requirements for my phone, the main hardware difference is probably ARM vs. Intel CPUs, but I don’t think that’s relevant to the topic.

7

What **LSLGuy **says above is correct. For a slightly less ‘wordy’ explanation: You call loading a new OS ‘installing’ on a laptop (or desktop) computer because it’s historically a much, *much *longer & laborious task and involves a PC’s hard drive, motherboard, on-board RAM, CD-ROM etc. whereas a phone was (and still is) a completely solid state device. Everything happens in memory so it’s always been simpler and, importantly, faster so it’s called ‘flashing’.

Well, that’s not really true, for the reasons I stated above. An SSD isn’t just memory, it’s a specific device (a solid state disk) and from a desktop/laptop’s OS point of view is no different than a spinning hard disk, with formatted physical sectors etc. Legacy of mechanical hard drives still being the dominant hardware.

8

I use the term Flash for updating the bios on a pc. EPROM’s require a special process to update the chip. Same thing with a phone.

You install software on a hard drive.

9

also keep in mind that the OS image for a smartphone is built specifically for that model handset, and includes all of the device drivers for the various hardware bits like cellular modem, USB interface, etc. So all you do is use whatever utility to write the image to ROM and there you go.

PCs can have umpteen millions of different combinations of hardware, so you have to load a generic OS build, then (if they’re not included) go and find all of the hardware drivers for peripherals and install them yourself.

10

Likewise, core dumps have always been called core dumps and always will be.

11

One reason for a computer’s OS being more complex, larger and on a disk instead of in ROM is the variability and complexity of computer hardware.

12

The software “install” process, especially the process of installing an entire OS on mainframe computers, has always been a rather involved process, requiring any number of (sometimes optional) steps. It was a job for a professional.

The steps might involve making back-ups of existing stuff (if you’re upgrading an existing system); planning your disk space usage and deciding how to partition your disk; running some kind of boot-strapping loader to put a bigger boot-strapping loader onto your disk; running that to create the file system structures on your disk and install some base version of the OS; then booting that and using the functions there to load all the rest of your OS; a few dozen required configuration options to walk through and zillions of other optional configuration details; restoring files as needed from your back-ups; and installing whatever user-level apps you need.

I did one such full upgrade (BSD Unix 4.2 to 4.3 on a mid-size VAX), circa 1975. The process took a week of planning and about 48 hours to actually do the install. I got too tired to continue after about 15 hours and went home. When I got back the next day, I found that one of the programmers had been in during my absence and did about 8 hours of installing.

And after that, the real fun started! Surprise, surprise! We discovered, the hard way, that the 4.3 restore program couldn’t restore from a 4.2 back-up. Oops. 4.3 came with a totally new kind of file system structure, and the back-up and restore programs both did some of their work at the file system structure level, and thus weren’t compatible.

13

You’re right.

The OP is not a technical guy & I had to simplify somewhere to keep the post length reasonable. I left out a couple sentences making explicit how term got embedded in the language and also that modern EPROM (or at least the type in phones) doesn’t use ultraviolet light erasers anymore but the term stuck with us.

Instead I just shortened “expose to UV light for umpteen minutes, blah, blah, blah … process … etc. etc.” to “flash of light.”

14

cripes, and I thought installing IRIX on an SGI workstation was a chore.

15

Apps are software.

16

Whoosh…

17

You’d be surprised how many people don’t know that.

18

Windows 10, coming out this year, is supposed to address this issue in a big way. It is a true general purpose operating system that can figure out what type of device it is being installed on and only install the components and features necessary for that device. For example, a desktop computer might receive a full-blown version of the OS while a smart-phone will get a stripped down version that only takes up a couple of gigabytes of space. It sounds promising and a step in the right direction.

19

Good point. Computers haven’t used core memory since the 70s*, but us old greybeard guys still think of it as “core”, not “RAM”. (Or more generically, “memory”.)

*with some exceptions. Back in the mid-90s, I worked on a computer system in the military that had just migrated from core within the last few years. They still had the core frames stored in the vault, simply because no current guidance or regulations covered the safe disposal of core storage devices which contained sensitive information, and no one would authorize any type of disposition plan that didn’t cite a controlling instruction for secure destruction. Catch-22.

20

Someone in this very thread said that apps come from a curated app store. I’ve got programs on my phone that didn’t, including some that I’m pretty sure Google does not approve of, and some that I wrote myself.