4. Backing storage units
- Backing storage units need for high capacity data storage devices that can store
data in a more permanent form for later retrieral, updating and referencing.
- Backing storage is also called secondary storage external storage and auxiliary
storage.
Chapter 2: MICOPROCESSOR.
Question 1. Cache Memory?
- Cache memory is a small amount of very fast store with faster access time than
the main memory.
- Cache memory is used to temporaryty store data instructions that are likely to be
retrieved many times, thus speeds up the processing of data.
- Sits between main storage and the processor acting as holding area through which
all data and instructions pass.
- Old data in the cache memory is over written by new then cache is full.
Question 2. Virtual Memory?
- Virtual memory makes use of both the main memory and backing store.
- In a virtual memory sys, each user has the illusion that his program is in the main
memory all the time.
- The sys maintains this illusion by keeping some of the “unused” portion of the
program’s code and data on a backing store device which is usually magnetic disk
- The movement of the unused portion from the backing store to the mian memory
is transparent to the users.
- Please refer to diagram for virtual memory.
Backing Store Main Memory
A3
A2
A1
A3
A2
A1
Virtual Memory
Chapter 3: BATCH/ ONLINE AND REAL TIME PROCESSING SYSTEM.
Question 1. Batch Processing System?
- Def: Computer processing does not begin until all the input data has been
collected and grouped together called Batched Generally data is accumulated for a
certain period of time or unitl a certain quantity.
- Ads:
Response time is not critical.
Need to process large volumn of data.
Computer efficiency is more important than response time.
- Dis:
Time between recording and processing of source document is long
Rereen normally required if errors are encountered.
Data is not current.
Error correction is more difficult.
Question 2. Online Processing System?
- Def: Inputs data enters the computer directly as soon as it is being transacted.
There information will be processed immediately and updated into the master file.
- Ads:
Enter availability of information for decision making.
More accurate data capture.
Schedules suits user.
- Dis:
CPU time is used less efficiently.
Random arrival of transactions, terminal operator process each
transaction separately.
More expensive than batch processing.
Question 3. Real Time Processing System?
- Def: One which controls the environment by receiving data processing them and
returning results sufficiently quickly to affect the functioning of the environment
at that time.
Response time is very critical and sufficient quick.
Expensive hardware & software.
Very complex in terms of hardware & software.
Chapter 4: PRINTERS AND TERMINALS.
Question 1. Classification of printers?
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