2. Why is DMA an improvement over CPU programmed I/O? 3. When would DMA transfer be a poor choice?
4. What is the average time to read or write a 512-byte sector for a typical disk rotating at
7200 RPM? The advertised average seek time is 8ms, the transfer rate is 20MB/sec,
and the controller overhead is 2ms. Assume that the disk is idle so that there is no
waiting time.
5. Disk requests come in to the disk driver for cylinders 10, 22, 20, 2, 40, 6, and 38, in that
order. A seek takes 6 msec per cylinder moved. How much seek time is needed for
(a) First-Come, first served.
(b) Closest cylinder next.
(c) Elevator algorithm (initially moving upward).
In all cases, the arm is initially at cylinder 20.
6. Describe how keyboard software works and which problems does keyboard software
need to handle?

Creating "smart interfaces" in all sectors of industry, government, and the public arena is one of the fastest growing hct areas. these interfaces model, interpret, and analyze such human characteristics as speech, gesture, and vision. the field of biometrics, in which humans authenticate themselves to machines, is an area of considerable interest to hct practitioners. fingerprint scans are one of the most frequently used biometric options, and this article, biometric student identification: practical solutions for accountability & security in schools, makes a case for the implementation of fingerprint scans in schools. critique the article, and answer the following questions: according to the author, what are the main benefits of adopting fingerprint scans in schools for student identification? according to the author, what are the main drawbacks of adopting fingerprint scans in schools for student identification? do you agree with the author's assessment of the pl

File account.java (see previous exercise) contains a definition for a simple bank account class with methods to withdraw, deposit, get the balance and account number, and return a string representation. note that the constructor for this class creates a random account number. save this class to your directory and study it to see how it works. then write the following additional code: 1. suppose the bank wants to keep track of how many accounts exist. a. declare a private static integer variable numaccounts to hold this value. like all instance and static variables, it will be initialized (to 0, since it’s an int) automatically. b. add code to the constructor to increment this variable every time an account is created. c. add a static method getnumaccounts that returns the total number of accounts. think about why this method should be static - its information is not related to any particular account. d. file testaccounts1.java contains a simple program that creates the specified number of bank accounts then uses the getnumaccounts method to find how many accounts were created. save it to your directory, then use it to test your modified account class.

Jean has kept the content of her website limited to what is important; she has also ensured that the text follows a particular style and color all throughout her website. which website features has jean kept in mind? jean has limited the content of her website to what is important; this ensures (clarity, simplicity, harmony and unity) of the content. she has also formatted the text in a particular style and color throughout her website, ensuring (balance, simplicity, consistency)