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designing microprocessor??

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Full Member level 3
Apr 29, 2005
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Under computer architecture course, I've to design a microprocessor with 8 bit data and 16 bit address ..minium 20 instructions and at least 2 mode to address. I need to write RTL for instructions and there timing diagrams and block diagram of the circuit.
Is there any software which helps to write RTL of instructions and displays its timing diagram.
Or How can I use VHDL or Verilog to solve my problem ?
Thank you.

There are some good examples of the CPU design on the network that you can look at to understand how a simple CPU code works.

For instruction, you just write a VHDL code for each and every one of them. Depending on the type of instructions, you can choose different ways of writing your code. The easiest one is to create a case statement for each instruction and then write the code there, the other way (a bit more complicated) is to write micro code and then use the 5 bits of the data to be the starting points for the instrucitons in your microcode memory.

When you are done with your coding, you use Modelsim to simulate your design and you will get the timing information for each instruction.

Search internet for "simple 8 bit CPU VHDL" and you will find some good sites with information,


You can download a software from altera
It is called Altera Max2 + plus

If you in urgent need for books then
Microprecessor design with VHDL is a good starting
download from here
**broken link removed**

you can also look at some free ip cores. for this logon to

Choose some computer architecture books, many of them have entire example of simple 8bit MCU implemention. You can refer to that.

To simulate it you'd rather write a test-bench and modeling a ROM in test bench to give instruncts for MCU running. During simulation dump out the waveform and check the result. You may run simulation by Cadence Verilog-XL/NC-Verilog; Synopsys VCS; Mentor Modelsim or Altera Maxplus

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