CSCI 206 Computer Organization Course Summary Major Course

CSCI 206 - Computer Organization Course Summary

Major Course Topics • • • Introductory C and immediate C ISA, machine instructions Assembly programming Data representations at the machine level Integer arithmetic – addition, subtraction, multiplication, and division • Floating point number representation and arithmetic • Computer organization basics – Fetch, decode, and execution cycle • Pipeline architecture • Performance

Classes of Computers

Programming in C and Assembly struct snode* list_find(struct slist *l, char *str) { struct snode *at = l->front; while (at != NULL){ if ( snode_cmp(at, str) == 0){ return at; } at = at->next; } return NULL; }

The C Programming Language (1) Variables, constants, statements Loops (for and while), functions, parameters Conditions (if-then-else) Pointers, arrays, linked lists Bit-wise operations Dynamic memory allocation and deallocation, memory leaking • Strings and structures • • •

The C Programming Language (2) • Compiling options with Makefile, and with multiple files • The process of producing machine code from source code. – Source code, object code, machine code, assembly code, library, system calls • Calling assembly code from a C program • Why C? Because C is a language that is close to the machine level and has a rich set of libraries that allow us to access operating systems services and hardware.

The Assembly and Machine Language (1) • Though we used RISC-V assembly language as our working language, the principles apply to all assembly languages • The same applies to the machine language we study (RISCV) • Assembly language is a symbolic representation of its machine language. • Information representation – Number systems, 2’s complement – Machine language vs assembly language vs high level language

The Assembly and Machine Language (2) • Six types of instructions, R, I, S, B, U, J – http: //www. eg. bucknell. edu/~cs 206/common-files/riscv-card-2 up. pdf • Assembly programming elements – Arithmetic, logical comparison, conditional and un-conditional jump – Data segment and code segment – Connection with C programs (. globl declarative) • Assembly language programming conventions – Procedure call convention, parameter passing (a 0 -a 7, and stack) – Jump and link (jal), return address preservation (the ra register) • Tools: RARS and actual programming on our riscv machine.

Information Representation 0 x 48656 C 6 C 0 x 6 F 20776 F 0 x 726 C 6421 Hello world! 0 x 000 0933 add t 0, zero 0 x. FFFF -1 0 x. FFFFFFFE -2 0 x 0000 BEEF 48879

Integer Arithmetic

Integer Arithmetic • A 1 -bit full adder – Multi-bits (e. g. , 32 bits) adder is made up of a cascade of 32 1 bit full adder • Integer arithmetic – Addition – Subtraction is just 2’s complementary addition – Multiplication is repetitive additions of unsigned values, compute the sign separately – Division is just repetitive subtractions, compute the sign separately.

IEEE 754 Floating Point Numbers

Floating Point Numbers (1) • Representation: IEEE 754 standard – Single precision (32 bit value): 1 bit sign, 8 bits biased exponent, and 23 bits mantissa (with hidden 1. 0) – Double precision (64 bit value): 1 big sign, 11 bits biased exponent, and 52 bits mantissa with hidden 1. 0

Floating Point Numbers (2) • Arithmetic – General algorithm: • • Line up the floating point by shifting the small value Do the operation (add or sub) Re-normalize the result Use of GRS (Guard, Round, and Sticky) bits to protect the loss of accuracy.

The Processor (1)

The Processor (2) • Single cycle datapath – Components needed to execute one instruction of any type, ALUs, registers, mux (multiplexers), instruction and data memory – How control signals are derived from the instruction

The Processor (3) • Pipelined datapath – Components needed to execute multiple instructions of any type in a datapath, ALUs, registers, mux (multiplexers), instruction and data memory, buffers in between the stages – How control signals are derived from the instructions – How information needed at each stage is passed along with the instruction – Hazards in pipelined datapath

Memory Hierarchy

Cache Memory • Memory hierarch – Registers, L 1 -cache, L 2 -cache, main memory, secondary storage • • • Direct mapped cache Fully associative cache N-way associative cache The computation of cache index and tags How to determine a cache hit (or miss) Cache lines with multiple bytes (words) as a block

Virtual Memory

Virtual Memory • Virtual memory gives the programmer a view that the memory addresses are contiguous and limitless • Memory management system maps virtual memory to physical memory, typically in a page system • The mapping is maintained by page table which typically is stored in memory • TLB is used for fast lookup and cache of page table entries • When a page needed is not in memory, a page fault occurs. The needed page must be brought in from disk – this is very expensive, avoid as much as possible by algorithms or hardware

Computer Organization, Operating System, and Applications ISA (organization) API

Operating Systems and Computer Organization • What we learned in computer organization provides a foundation for the operating systems course • OS is a resource manager or an interface between applications and the computer hardware • OS does so (interface) by providing accesses to system resources through well-defined APIs for application programmers • OS is written in system programming languages such as C. Linux is written in C with a small portion in assembly