Published source code for Doom port for push-button phones based on Spreadtrum SC6531 chip. Modifications of the Spreadtrum SC6531 chip occupy about half of the market of cheap push-button phones of Russian brands (the rest belongs to MediaTek MT6261, other chips are rare).
What was the difficulty of porting:
- There are no third party apps available on these phones.
- Small amount of RAM - only 4 megabytes (brands / sellers often indicate this as 32MB - but this is misleading, since megabits, not megabytes).
- Closed documentation (you can only find a leak of an early and inferior version), so a lot was mined using the reverse engineering method.
The chip is based on the ARM926EJ-S processor with a frequency of 208 MHz (SC6531E) or 312 MHz (SC6531DA), can lower the frequency to 26 MHz, ARMv5TEJ processor architecture (no division and floating point operations).
So far, the work of only a small part of the chip has been investigated, these are USB, screen and keys. Therefore, you can play only when the phone is connected to the computer with a USB cable (resources for the game are transferred from the computer), and there is no sound in the game.
It is currently running on 6 out of 9 tested phones based on the SC6531 chip. To put this chip into boot mode, you need to know which key to hold while booting, keys for tested models: F + F256: *, Digma LINX B241: center, F + Ezzy 4: 1, Joy's S21: 0, Vertex M115: up, Vertex C323 :0.
Two videos were also published: with a demonstration phone games and launch on 4 more phones.
PS: Similar was posted on OpenNet, news from me, only edited by site admin.
Without a license, it's hard to say what license should be for the code obtained by reverse engineering, consider it as copyleft - copy and change, let's change others.
The game Doom was used to attract attention, as an example, I would like a free firmware for feature phones. Their chips are much more powerful than they are used in the firmware. Moreover, hardware is cheap and mass-produced, unlike rare phones with βopenβ operating systems or those that allow you to execute your own code. So far I have not found anyone to cooperate, and reverse engineering is hard fun. For starters, it would be nice to find SD card management and power management so that these phones can be used as a game console. In addition to Doom, you can port the NES / SNES emulator.
Source: linux.org.ru