Exam mistakes Flashcards
(22 cards)
Why is Harvard Architecture preferred over Von Neumann
Instructions and data are accessed simultaneously
Instructions and data stored in parallel, so reduces ‘bottleneck’ problem
Avoids possibility of data being executed as code (which is one method that can be exploited by hackers)
When normalising a floating point number, when should the exponent be positive?
When you’re moving the decimal point to the left (so the exponent increases to accomodate for it)
When normalising a floating point number, when should the exponent be negative?
When you’re moving the decimal point to the right (so the exponent decreases to accomodate for it)
What effect does increasing the mantissa have?
- Decreases exponent, so reduces range but increases precision
What effect does increasing the exponent have?
- Decreases mantissa, so increases range but decreases precision
How many bits in a byte?
8
What are the steps required in converting from floating point to decimal?
Find value of exponent
Shift mantissa by bits of exponent
If mantissa is negative, convert to a positive value
How to find absolute error?
(intended value) - (actual represented value)
How to find relative error?
absolute error/intended value x 100
How do you create a table in SQL
CREATE TABLE tablename (
)
How do you add a column to a table?
ALTER TABLE tablename
ADD columnname Datatype
How do you delete a column in a table?
ALTER TABLE tablename
DROP COLUMN columnname
How do you change the datatype of a column?
ALTER TABLE tablename
MODIFY COLUMN columnname newdatatype
How do you insert values into a table?
INSERT INTO tablename(column1, column2…)
VALUES(value1, value2, …)
How do you update a record
UPDATE tablename
SET column1 = value1, column2 = value2 etc
WHERE columnX = Value
How do you delete a record
DELETE FROM tablename
where columnX = value
What are the conditions for Vernam Cipher?
The key must be (at least) as long as the data to be encrypted/plaintext;
The key must not be reused // key must only be used once;
The key must be (truly) random;
The key must be kept securely / not revealed / only known by user(s);
What are the principles of operation of an optical disk?
- A high powered laser is used to burn “pits” into the disc. Areas which have not been pitted are called lands. Pits are represented with 0s and the transition between a pit and a land is represented with a 1.
A low powered laser is used to shine light onto the disk. It measures the intensity of the light that has been reflected back. Areas which light has not been reflected well are pits, and areas which light has been reflected well are lands.
other forms of discs such as CD RW may use a high powered laser to burn a spot, and then polarise the spot with a magnet before cooling or using a phase change alloy.
How can a server’s performance be increased?
Talk about:
Hardware improvements
Network design
Database design and software
Hardware improvements
- More processor cores (more instructions can be executed simulataneously)
- Use SSD over HDD (Faster read write speed)
- Increase address bus width and data bus width, word lines
Network improvements:
- Use wired network over wireless network
- Use star topology
- Use NICs with high data transfer rate
Database design and software
- Normalise database to 3NF
- Software should use efficient searching algorithms
- Software should be compiled
Why is technology making it difficult for legislators to prosecute cyber criminals?
Criminals can hide their location/use VPN, hide MAC address, and can maintain anonymity
Tech evolves quickly so more new types of crime becoming possible
Global nature of Internet means crimes may be committed in one country from outside its direct jurisdiction
How does increasing data bus width improve processor performance?
Increases the amount of data that can be transferred at one time
In this SQL query querying two tables, what are the mistakes? :
SELECT VetForename, VetSurname
FROM Surgery, Vet
WHERE Town = Torquay
What other database question mistakes could be there
- ‘Torquay’ is a string and so should be in quotations
- There is no join clause linking the two tables that are being searched
Datatypes being referred to before the identifier, no data types for some entities, etc
