I have downloaded most of the CentOS 7 image from : http://mirror.centos.org/altarch/7/isos/i386/ and tried to install it on different SD cards. Nothing on boot, multi color screen locked. Is it sure that it can work with the Pi model B+ V1.2 ?
I have downloaded most of centos 7 img from : http://mirror.centos.org/altarch/7/isos/i386/
That will not work. "i386" refers to the Intel 80386 instruction set architecture (ISA). This was the prevailing 32-bit ISA used by chip makers like Intel, AMD and IBM until the development of the x86-64 (aka. AMD64) ISA now used in most personal computers.
However the SoC (there are actually three slightly different ones) used on the Raspberry Pi, like most low power mobile and embedded devices, is built on a processor designed with an ISA from the ARM family of architectures.
When software is compiled to machine code, that machine code is ISA specific.
The prevailing operating system used on the Pi, Raspbian, uses the lowest common denominator, ARMv6, since this will work on all three SoCs (the BCM2835 used on all models except the 2 and 3, the 2836 used on the Pi 2, and the 2837 used on the Pi 3).
ARMv6 is actually relatively obscure, but the next version up, ARMv7, is very widespread, so most major linux distributions have an existing repository easily adapted to the Pi 2 or 3 (ARMv7 will not work on the other models). The Pi 3 is actually designed on the ARMv8 64-bit ISA, but ARM architectures are backward compatible. There is also a collection of ARM 64 distros that target the Pi 3 specifically.
CentOS has both ARMv7 and ARMv8 distros for various dev boards. Unfortunately, as just explained, these will not work on a B+. There is a more limited selection of operating system compilations for the ARMv6 models. The most prevalent are Raspbian and Arch. Our fairly exhaustive list is here:
Beware there are distros specific to the 2 and 3 in there, hopefully they are all clearly labelled. Whatever you install, make sure first it is an ARMv6 version. Sometimes they might be referred to as ARM1176JZ(F)-S since this is the particular ARMv6 implementation used in the BCM2835 core.
raspberry pi model 3 b+ are, new model, it`s only supported by raspbian, today, i think. dont waste your time, use raspbian os.https://www.raspberrypi.org/downloads/ , download the raspbian , if you use raspberry 3b+