SPDY
A FASTER RISC PROCESSOR
DEVELOPERS
Alankrita Gautam
Anisha Grover
Rajat Srivastava
Samarth Saxena
Shashank Mehta
Yatin Tyagi
Under the able guidance of
DR. VASKAR RAYCHOUDHARY
AIM
To develop an ISA that
- Improves the speed of common cases
- Remove unnecessary hardware
-
Reduce power consumption
DESIGN PRINCIPLES
Design Principle 1
Simplicity favors regularity
Design Principle 2
Smaller is faster
Design Principle 3
Make the common case fast
Design Principle 4
Good design demands good compromises.
Do one thing and do it better than anyone else
-- Jeff Hoffman
Make
the
common
case
fast
INSTRUCTION SET ARCHITECTURE
KEY FEATURES
- Variable size of opcode field
- No. of Registers: 32
- Length of Registers: 24 bits
- Register Classification
- Program Counter
- 3 Loop Control Registers
- 12 Saved Registers
- 14 Temporary Registers
INSTRUCTION FORMATS
INSTRUCTION SIZE
SPDY has a reduced instruction size of 24 bits compared to MIPS 32 bits, thereby enabling lesser instruction memory consumption.
Further, because of the varying opcode field size,we succeeded in increasing the offset field size to 15 bits (in case of Branch Format) thereby increasing the memory reach to a greater extent, instead of original 15 bits
OPCODES
ARITHMETIC FORMAT
F: Format field
RS1: Source Register
RS2: Second Source Register
Rd: Destination Register
Opcode: Operation code
example: add $s1, $t1, $t3
BRANCH FORMAT
F: Format field
Offset: Offset to Address
Opcode: Operation code
example: br loop1
IMMEDIATE FORMAT
F: Format field
RS1: Source Register
Rd: Destination Register
Offset: Offset to Address
Opcode: Operation code
example: addi $s1, $s1, 4
Basic part is now done
So what is new in spdy?
DESIGN PRINCIPLE 3
Make the common case fast
DESIGN PRINCIPLE 3
Make the common case fast
LOOPING IN MIPS
HOW IMPORTANT IS LOOPING?
Looping is one of the most basic parts of any program.
Simple counters that go from 0 to, lets say, 10, are used in many programs.
In fact, many programs such loops are also nested.
So if these loops become faster, the program runs faster.
LOOPING IN SPDY
LOOP CONTROL DATAPATH
COMPONENTS USED
The components used are :
Program counter, Instruction memory, Data memory, Control unit,Registers, ALUs, Multiplexers
CONTROL UNIT
CONTROL UNIT RTL
ALU
ALU RTL
REGISTER FILE
REGISTER FILE RTL
MEMORY
Memory Size of the SPDY microprocessor is 128 X 24 bits
LOOP CONTROL RTL
DATAPATH
DATAPATH
risc
By shashankm
