How is software (not games and applications) programmed on mobile phones?

Question

Programming

Hello. I could not find suitable information on the Internet, so I'm asking a question here. Please tell me how phones were programmed before, about 10-20 years ago? Where can I learn more about mobile phone architecture? Tell me tutorials or books on programming firmware for mobile phones? The question relates to programming so-called "firmware", and not to creating applications and games for phones. And, importantly, how to find out information about the phone (not the IMEI and phone name, but the software name, the name of the microcontroller, and, if possible, how to get the firmware code from the phone)? Ultimate goal: there is a Chinese push-button mobile phone, it is not clear what origin, it works, but there are many bugs in the software. I would like to write firmware on it and rewrite the microcontroller.

Answer 1

if you really want to comprehend the essence of work and writing software for mobile phones, then I will give the following advice: buy a gsm module, find (it will not be difficult) a datasheet for it, a cheap lcd display, a primitive keyboard, buy a microcontroller that is convenient for you (for the price) and study, train, it will be interesting in the sense that there will be a lot of information on this subject and you will have specific questions and people will be happy to answer them. roughly speaking, make your phone, well, at least try it. It will be more exciting and interesting, because. what you want to do now is a disastrous thing, no one will give you the source code, but without knowing the architecture, the addresses of the microcontroller register (installed on this particular Chinese phone), even an experienced person will do nothing if they wish

Answer 2

If you have zero knowledge, it will be problematic ... Open the phone, look for datasheets for local mikruhi. Find (if you're lucky) a processor - read hefty programming manuals on it. Along the way, learn its assembler and IDA (if it supports it). Information about the methods of flashing and merging with chances is on the internet, but it's probably not like two fingers on the asphalt ...

Answer 3

Impossible. You set an almost impossible task - to write a firmware for noname Chinese controller, it is not clear what architecture, it is not clear by what means. Reversing finished devices even with documentation is a job for high-class specialists with extensive experience, and you are going to learn from this.
It is almost impossible to get documentation for ancient Chinese MKs, and even if it does, then, surprise, it will be in Chinese.
If you want to learn how to work with microcontrollers - buy a demo board of some STM.
If you want phone architecture, look towards open source projects, for example Openmoko
And it’s better not to go into ancient antiquity, there is a solid custom, which sometimes you can’t understand, even with diagrams.

Answer 4

Well, it's easy. Start from the opposite. With ASM, then processors. If you wish, you will figure it out in a couple of weeks, until you understand and feel confident.