since my early days as a sophomore,i always wanted to build my own microprocessor which i recently came to know,can be done with the help of fpga(along with VHDL),but i dunno know where to start and whether building a 8-bit microprocessor is difficult? HELP ME OUT

 

http://www.instructables.com/id/How-to-Build-an-8-Bit-Computer/

 

Divide and Conquer
You need to break the project up into manageable chunks. I would start with the ALU (Arithmetic Logic Unit). The basic function is to take two 8-bit numbers and an optional Carry-In and produce one 8-bit result and a Carry Out. This is a combinatorial circuit that does not require any storage elements (flip-flops). Once you have this part nailed down you can add registers for operands and results, memory, and control circuits.

Good Luck

 

You might have a look here http://opencores.org/projects

 

One day i started making a "message in space" without microcontroller.

I had some keys to set the address, and enter data into a RAM, and then also oscillator to cycle through the address.

All you need is comparators, and branching logic, and some kind of ALU.

Since it is just for fun, it does not need to be able to do meaningful maths.

It would be a lot of effort anyway.

It has been done with FPGA already by some people.

A microprocessor is using external RAM and program ROM and pheripherals, while a microcontroller has it all on board.

 

I recommend you start by reading this book:

http://www.amazon.com/Microprocessor-Design-Using-Verilog-HDL/dp/0963013351

 

Member vead has been recently posting to ask questions similar to yours.

One of his (many) threads is here.

Not in that subject myself, he seems to be closer to get some concrete results.

Buena suerte.