Friday, December 4, 2020

India's First Indigenous Microprocessor!

The SHAKTI Processor Program, was started as an academic initiative back in 2014 by the Reconfigurable Intelligent Systems Engineering (RISE) group at IIT-Madras. It is completely Open-source. The major aim is to bridge the gap between academia and industry, to provide innovative and customized solutions.

What is SHAKTI?

SHAKTI is an open-source initiative by the RISE group at IIT Madras. Shakti is building many processors based on the RISC-V instruction set. The processors are based on 22nm FINFET technology. They have been broadly categorized into "Base Processors", "Multi-Core Processors" and "Experimental Processors". They currently have 3 core variants known as the E class , C class and I class. E class is for embedded application like robotic controller boards and IoT boards. C class is the controller class for mobile like applications and can run at upto 1.5 GHz. I class is the performance oriented and can run at around 2.5 Ghz clock speed . They also have plans for multi core processors that will involve combinations of C class cores and I class cores .They also have plans for a super computer class processor which will be called Parallel shakti or para shakti.

These chips could be used in ISRO’s NavIC satellites in the future. C class cores will mostly compete with ARM . The one who design chips inside your phones . Companies like Qualcomm, Samsung and MediaTek use these designs .you must have heard words like cortex A57 or something similar. These are designed by ARM. More on that later . 2 C class processors were fabricated . One by intel based on 22 nm called RISECREEK and the special one in India at the Chandigarh facility partly run by ISRO based on 180 nm called RIMO.

RISC-V ISA Overview

RISC-V (pronounced “risk-five”) is a free and open Instruction Set Architecture (ISA) enabling a new era of processor innovation through open standard collaboration. RISC-V was originally designed to support computer architecture research and education. But now it has become a standard free and open architecture for industry implementations. RISC-V ISA is defined as a base integer ISA, which must be present in any implementation, plus optional extensions to the base ISA. Each base integer instruction set is characterized by the width of the integer registers and the corresponding size of the address space and by the number of integer registers. RISC-V is little-endian and comes in 32 and 64 bit flavors. For both, int is 32 bits. Pointers and long are of native register size. Signed values are always sign extended in a larger register. Unsigned 8/16-bit values are zero extended. Unsigned 32-bit values are sign-extended. RISC-V has been designed to support extensive customization and specialization. RISC-V spec has two volumes, User level Spec and Privilege level Spec.

Why is Shakti different ?

Mainly because it uses the open source RISC-V instruction architecture . Intel/ AMD and ARM have their own architectures or the language with which you communicate with the processor . Intel and AMD has something called X86 and ARM uses their own . They do not share this with anyone .If you reverse engineer and make one you will have to deal with court cases .

RISC-V is an open source instruction set architecture .Suppose you go to buy a car , but you are forced to buy a truck along with it . If you want to buy a car , you have to also buy the truck . This is the problem with INTEL and ARM . You cant choose what specific instructions you want to use . You have to buy them all . We can use RISC-V to make a custom chip design for our needs . As a bonus many people responsible for RISC-V are also Indian. They also have their own company called sci-five which makes designs like Shakti . The startup coming out from IIT Madras will be called InCore. Keep a note of that , will require after some time .This advantage gives us the power to design the chips of our need with good security . Will detail this later .