# Recent activity by G Phalkey

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Since it is a Bottom Up Parser do we need to evaluate expressions following Right Hand Derivations or Left Hand Derivations,i.e. should we evaluate D -> d first or B -> B first?
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The value of a $\text{float}$ type variable is represented using the single-precision $\text{32-bit}$ floating point format of $IEEE-754$ standard that uses $1$ $\text{bit}$ for sign, $\text{8 bits}$ for biased exponent and $\text{23 bits}$ for the ... $−14.25$. The representation of $X$ in hexadecimal notation is $C1640000H$ $416C0000H$ $41640000H$ $C16C0000H$
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Consider the following statements: S1: The sum of two singular $n \times n$ matrices may be non-singular S2: The sum of two $n \times n$ non-singular matrices may be singular Which one of the following statements is correct? $S1$ and $S2$ both are true $S1$ is true, $S2$ is false $S1$ is false, $S2$ is true $S1$ and $S2$ both are false
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A bit-stuffing based framing protocol uses an $\text{8-bit}$ delimiter pattern of $01111110.$ If the output bit-string after stuffing is $01111100101,$ then the input bit-string is: $0111110100$ $0111110101$ $0111111101$ $0111111111$
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Given Set $A= {2, 3, 4, 5}$ and Set $B= { 11, 12, 13, 14, 15}$, two numbers are randomly selected, one from each set. What is the probability that the sum of the two numbers equals $16$? $0.20$ $0.25$ $0.30$ $0.33$
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A $CFG$ $G$ is given with the following productions where $S$ is the start symbol, $A$ is a non-terminal and $a$ and $b$ are terminals. $S \to aS \mid A$ $A \to aAb \mid bAa \mid \epsilon$ Which of the following strings is generated by the grammar above? $aabbaba$ $aabaaba$ $abababb$ $aabbaab$
$(0.5)_{10}$ in IEEE 754 Single precision floating point representation $(0.5)_{10}$ = $(0.1)_{2}$ here $(0.1)_{2}$ should be represented in SUBNORMAL form Or Normalized for ..??? here $(0.1)_{2}$ * 2^{0}$...E = 0 and no leading 1 ..will it be represented in SUBNORMAL form ?? 1 answer 10 2 answers 11 How can we convert a signed number to it's equivalent unsigned number? Let's say I have signed number as -2 now what would be it's equivalent unsigned representation. Thanks! 1 answer 12$\text{How we can represent a number like 234.4437 using 2's complement representation?}\text{Or we are supposed to represent it using floating point representation? Please explain }$1 answer 13 What is the reason for Belady’s Anomaly,I am aware that it is not a stack based algorithm and for a certain set of pages it shows this anomaly where the increase in page frame increases the page fault rate. 0 answers 14 1 answer 15 Please check whether the given explanation is correct or not. 1 answer 16 A Computer system implements 8 kilobyte pages and a 32-bit physical address space. Each page table entry contains a valid bit, and the translation. If the maximum size of the page table of a process is 20 megabytes, then what will the length of the virtual address ... .in/8247/gate2015-2_47 The above question related to this gate question.But when I tried i got 33 bit but i choose 30 bits 4 answers 17 Let the page fault service time be$10$milliseconds(ms) in a computer with average memory access time being$20$nanoseconds (ns). If one page fault is generated every$10^6$memory accesses, what is the effective access time for memory?$21$ns$30$ns$23$ns$35$ns 3 answers 18 Q. Suppose you have a computer system with a 48-bit logical address, page size of 16KB and 4 bytes per page table entry. If we have a 48MB program such that the entire program and all necessary page tables are in memory. Assume that each page table at diff level fits in a single page.How much memory is used by program, including its page tables? 2 answers 19 A demand paging system has page fault service time as 125 time units if page is not dirty and 400 times units of page fault service time if it is a dirty page. Memory access time is 10 time units. The probability of a page fault is 0.3. In case of page fault, the ... dirty is P. It is observed that average access time is 50 time units. Then, the value of P is ______? [upto four decimal places] 2 answers 20 A 32-bit machine has a page/frame size of 1 KB. (i) What is the size of the complete first-level (primary) page table for a process? (ii) If page tables are also stored using paging, how many levels of paging will be required? 2 answers 21 Please Explain. 1 answer 22 Whenever Questions like:- (Example is shown below) is given and asked that say what is the turnaround time for$6k$Process then we will always assume memory to have fixed length partition right??? cuz they have given different partition sizes in$KB$so say if a process allocates$2k$... 1 answer 23 Explain Last In First Out (LIFO) and MRU with this example and find a number of a page fault. Question: Let the number of the frame in main memory is 5. Reference String: 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 answer 24 Given 64 bit logical space, Page Size =$4KB$. Do the three level paging? My Solution:- 1. Since address space is =$ 2^{64} Bytes$Page size =$2^{12}$Bytes. Number of entries in third level Page table is :-$2^{64} / 2^{12}$=$2^{52}$. Size of third level ... three levels as:-$1st$level$2nd$level$3rd$level Offset$ 32101012$Please explain how did they find this out ? Please :) 0 answers 25 In a 32-bit machine we subdivide the virtual address into 4 segments as follows: 10-bi 8-bit 6-bit 8 bit We use a 3-level page table, such that the first 10-bit are for the first level and so on. Page Table Entry Size is 2B 10-bit 8-bit 6-bit 8 bit What ... greater than page size which is 2^8 so outer most page cannot fit in one page table But outermost page table should fit in one page ?? ref: 1 answer 26 Suppose : TLB lookup time = 20 ns TLB HIT ratio = 80% Memory access time = 75 ns Swap page time = 500000 ns 50% pages are dirty and os uses a single level page table a) what is EMAT if we assume page fault 0%? b) what is EMAT if page fault 10% ? In both cases assume cost to update TLB , page table , frame table is negligible (if needed). 1 answer 27 CPU generates logical address and that logical address is converted to physical address. What does this means exactly ?? Assume run time binding is used. When process P1 is loaded in memory lets say at 10k Lets say OS scheduler schedules P1,so CPU should start ... cpu generates address means we put that address in MAR to get some data/instruction from memory right ? Please help me in this 0 answers 28 I have watched two video lectures on OS memory management (PK Biswas and IISc Mathew Jacob). In both lectures they say that the compiler assumes (while compiling and generating the logical addresses to instructions) that for each process, all of the virtual address space is ... the page table of each process consists of same number of entries..? Is it the real reason to use valid/invalid bit ? 2 answers 29 Consider a system with byte-addressable memory,$32-bit$logical addresses,$4kilobyte$page size and page table entries of$4bytes$each. The size of the page table in the system in$megabytes\$ is_________________.