In this project, you will be completing the design of a simple general purpose processor using Xilinx ISE Schematic Capture.
computer science
Description
The Problem
In this project, you will be completing the
design of a simple general purpose processor using Xilinx ISE Schematic
Capture.
DISCLAIMER: The processor we are working with
is a very basic 8 bit single cycle processor with no data memory. While it is a
good representation of a general purpose processor and is good for education,
commercial processors are typically more complex.
A skeleton has been provided that contains
various aspects of the processor already designed. You will be completing the
Arithmetic Logic Unit, Register File and Instruction Memory of the simple
processor.
Below is a description of these units as it
pertains to this processor. You will need to use these descriptions as well as
the information in the architecture section to fully build these units.
Arithmetic Logic Unit (ALU):
As covered in class, the arithmetic unit does
the arithmetic and logic lifting for the processor. This ALU is an 8 bit ALU
and can do 8 different operations as described in the table below. You will
build the components for these logic and arithmetic operations.
|
Opcode |
Operation |
|
000 |
O = B |
|
001 |
O = A ^ B (bitwise xor) |
|
010 |
O = A AND B (bitwise and) |
|
011 |
O = A OR B (bitwise or) |
|
100 |
O = A + B (addition) |
|
101 |
O = A - B (subtract) |
|
110 |
O(7) = 0, 0(6:0) = B (7:1) (logical shift right) |
|
111 |
O = A * B (multiplication) |
In addition to the operations, the ALU will
also help generate flags based off the output. You do not have to create the
flags but will need to create the input
values for the carry flag multiplexor.
ALU inputs:
A(7:0):
8 bit data to be operated on. This comes
from the register file, read data
a(R_data_a).
B
(7:0):
8 bit data to be operated on. This can come
from the register file, read data b (R_data_b)
or the data input to the processor.
Opcode
(2:0):
This picks the operation to be done. The opcode comes from instruction bits 6
down to 4.
