NTP-microprocessor

• Overview

  A real time Microprocessor impemented in verilog and tested on Xilinx Artix-7 FPGA.

  It's a RISC based 8 bit 5 stage pilelined processor with 28 bit instruction format and 579.67 Mhz clock frequency.

  Individual module implementations for:

  • Instruction Fetch
  • Instruction Decode
  • Execution Block
  • Data Memory Block
  • Write Back Block
  • Dependency Check Block
  • Jump Control Block
  • Stall Control Block
  • Register Bank Block

• Specifcations and Features

  • 8-bit Processor.
  • Instruction Size 24-bit.
  • 28 Distinct Instructions.
  • Fixed Instruction Size (24 bits).
  • RISC based architecture.
  • 5 Staged pipelined processor.
  • Maximum Clock Frequency 579.374 MHz.
  • 32 Registers.
  • Ideal CPI = 1.
  • Five types of Instruction format (R, I, J, M and I/O type).
  • Harvard type architecture as there are separate storage blocks and signal pathways are provided for data memory and program memory.
  • Two types of addressing modes register direct mode and register immediate addressing mode.
  • Simpler Architecture.
  • CPI = 1.33333333.
  • Program Memory 768 bytes.
  • Data Memory 256 bytes.
  • 21 pins (data_in 8, data_out 8, clk, reset, Vcc, Ground and Interrupt each)

• Block Diagram

Note:- All the modules contain clock (clk) and reset as inputs.

• How to Use

  • After downloading this repository just open NTP-Microprocessor.xise file in Xilinx-ISE.
  • Go to Simulation from the menu shown on top left corner and run Microprocessortb.v file to check simulation results.
  • Or Else upload .bit file on Artix-7 FPGA

• In order to write your own assembly code in Assembly_Program.COE in memory_initialization_vector in Hexadecimal format.

• Regenrate Program Memory's IP Core (ROM) and select Assembly_Program.COE while initializing it.

• If Problem still persists you can raise an issue or contact me on [email protected]

  For More Details Refer Report.pdf

  Opcodes and Operations

  Sr No.	Instruction	Opcode	Operation in Execution Block	Flags Affected	Type
  1	ADD	00000	ans_ex = A + B	Parity, Overflow, Zero, Carry	R-type
  2	SUB	00001	ans_ex = A - B	Parity, Overflow, Zero, Carry	R-type
  3	MOV	00010	ans_ex = B	Parity, Zero (Reset other flags)	R-type
  4	AND	00100	ans_ex = A & B	Parity, Zero (Reset other flags)	R-type
  5	OR	00101	ans_ex = A | B	Parity, Zero (Reset other flags)	R-type
  6	XOR	00110	ans_ex = A ^ B	Parity, Zero (Reset other flags)	R-type
  7	NOT	00111	ans_ex = ~B	Parity, Zero (Reset other flags)	R-type
  8	ADI	01000	ans_ex = A + B	Parity, Overflow, Zero, Carry	I-type
  9	SBI	01001	ans_ex = A - B	Parity, Overflow, Zero, Carry	I-type
  10	MVI	01010	ans_ex = B	Parity, Zero (Reset other flags)	I-type
  11	ADI	01100	ans_ex = A & B	Parity, Zero (Reset other flags)	I-type
  12	ORI	01101	ans_ex = A | B	Parity, Zero (Reset other flags)	I-type
  13	XRI	01110	ans_ex = A ^ B	Parity, Zero (Reset other flags)	I-type
  14	NTI	01111	ans_ex = ~B	Parity, Zero (Reset other flags)	I-type
  15	RET	10000	Hold previous ‘ans_ex’	Reset all flags	J-type
  16	HLT	10001	Hold previous ‘ans_ex’	Reset all flags	---
  17	LD	10100	ans_ex = A	Reset all flags	M-type
  18	ST	10101	ans_ex = A	Reset all flags	M-type
  19	IN	10110	ans_ex = data_in	Parity, Zero (Reset other flags)	I/O-type
  20	OUT	10111	Hold previous ‘ans_ex’ data_out = A	Reset all flags	I/O-type
  21	JMP	10101	Hold previous ‘ans_ex’	Reset all flags	J-type
  22	LS	11001	ans_ex = A << B	Parity, Zero (Reset other flags)	R-type
  23	RS	11010	ans_ex = A >> B	Parity, Zero (Reset other flags)	R-type
  24	RSA	11011	ans_ex = A >>> B	Parity, Zero (Reset other flags)	R-type
  25	JC	11100	Hold previous ‘ans_ex’	Reset all flags	J-type
  26	JNC	11101	Hold previous ‘ans_ex’	Reset all flags	J-type
  27	JZ	11110	Hold previous ‘ans_ex’	Reset all flags	J-type
  28	JNZ	11111	Hold previous ‘ans_ex’	Reset all flags	J-type

  Note -: Arithmetic operations are on 2’s complimented numbers.

  

  • Simulation Results

  • Addition

  • Multiplication

• Comparison of our design with 8085

Our Processer	Intel 8085
RISC Based Architecture	Semi CISC Based Architecture
8-bit Address bus	16-bit Address bus
8-bit CPU	8-bit CPU
Max Clock frequency 579.374 MHz	Clock frequency 3-6 MHz
5 staged pipelined processor	Single stage non-pipelined processor
21 pins	40 pins
32 Registers	6 Registers (B, C, D, E, H, L) and 1 Accumulator
External Memory cannot be added	External memory can be added
Harvard based architecture	Von Neumann based architecture
Fixed Instruction size(24 bits)	Varying Instruction size (8-24 bits)
28 distinct Instructions	74 distinct instructions
Program memory is 768 bytes and Data Memory is of 256 bytes	Program memory and Data Memory combined is of 65536 bytes
No Accumulator	Contains Accumulator
Only one Interrupt	Five hardware Interrupts
No Stack Pointer	Stack Pointer

• Execution Block

• Program Memory

• Register Bank

• Data Memory

• Stall Control

• Write Back

• Jump Control

• Dependency Check