Answer and Explanation:
A TM with doubly infinite tape can simulate an ordinary TM. It marks the left-hand end of the input to detect and prevent the head from moving off of that end. To simulate the doubly infinite tape TM by an ordinary TM, we show how to simulate it with a 2-tape TM, which was already shown to be equivalent in power to an ordinary
TM. The first tape of the 2-tape TM is written with the input string, and the second tape is blank. We cut the tape of the doubly infinite tape TM into two parts, at the starting cell of the input string. The portion with the input string and all the blank spaces to its right appears on the first tape of the 2-tape TM. The portion to the left of the input string appears on the second tape, in reverse order.
Answer:
A tape drive provides sequential access storage, unlike a hard disk drive, which provides direct access storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data.
Explanation:
Architecturally tape drives are sequential storage, meaning that if you need to access some data at the end of the tape you needed to seek to the end and retrieve it. This can take seconds or minutes. Disks, OTOH are random access. Some hard drives use rotating media and movable heads , so the seek times are instantaneous , at least compared with tape drives. However, like tapes, there is a big advantage to using a rotating hard drive as sequential storage. It takes time, measured in milliseconds, for a head to move to another track. So traditionally, random access is much slower than sequential access.
SSDs have no internal moving parts so random access occurs in the same time frame as sequential access. Moreover, these drives usually have very high performance. For example, they can saturate a SATA data link, meaning that the SATA connection to the motherboard is now a bottleneck in disk access.
At one time tape drives were very popular. They were a low-cost alternative to using disks as backup. They were especially useful when IBM invented the Winchester “fixed” drive. This meant that the hard drive is fixed within its enclosure like they are today. Prior to this one could remove the drive pack and replace it. This was helpful when upgrading to a new version of the operating system as it was simple to replace the older drive pack should there be a problem.
Tape drives can be used in larger data centers, due to the fact that tape volumes can be removed and replaced so that the actual tape drive can backup many disk sets. Also the tape volumes can be stored off-site or in a fire-proof vault so this is valuable in a data recovery scenario.
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Analog computers store data in a continuous form of physical quantities and perform calculations with the help of measures.
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DSL - DSL stands for Digital Subscriber Line. This technology came after the Dial Up technology for connecting to the Internet. The big disadvantage of Dial-up technology was that when you were talking on the phone, you could not use the Internet and vice-versa. However, although DSL technology used the regular telephone line , it worked on frequencies different from the telephone. So you could use the phone and the Internet at the same time.