REV Flashcards
What are the four layers of the TCP/IP stack?
Application layer
Transport layer
Internet layer
Link Layer
What does TCP/IP
Transmission Control Protocol/Internet Protocol
What is the function of the application layer?
The application layer specifies what protocols need to be used
What is the role of the transport layer?
- Splits up data into packets
- Establishes end-to-end connection
what is the role of the internet layer?
Links the routers
What is the function of the link layer?
Adds the MAC addresses to the packets
What does the Memory Address Register do?
The MAR holds the address of a location that is to be read from or written to
What does the Memory Data Register do?
The MDR Temporarily stores data that has been read or data that needs to be written.
What happens during the fetch phase?
- The address from the PC is copied to the MAR
- Instruction held at that address is copied to the MDR by the data bus
- PC is incremented by 1
- The value of the MDR is copied to the CIR
Explain the Von Neumann Architecture
- Shared memory space for instruction and data
- Can only perform one instruction at a time
- Registers are used for fast access to instructions and data
Explain the Harvard Architecture
- instruction and data stored in separate memory units
- Each has its own bus
- Reading and writing data can be done at the same time as fetching an instruction
- used by RISC processors
What are the similarities and differences between paging and segmentation?
Both are used when RAM space is insufficient
Paging uses equal-sized sections called pages
Segmentation uses variable-sized logical sections called segments
What are the stages of compilation?
Lexical analysis
Syntax analysis
Code generation
Optimisation
What happens during lexical analysis?
- Whitespaces and comments are removed from the code
- remaining code is turned into a series of tokens
- symbol table is created to keep track of the tokens
What happens during syntax analysis
syntax analysis will produce an abstract syntax tree that checks that the code written has valid syntax
What happens during code generation?
compiler converts the results syntax analysis stage into object code
What happens during optimization?
insignificant bits are removed
Explain the stages of the interrupt service routine ISR
- Interrupt register checked at the end of each F-D-E cycle
- If there is an interrupt with a higher priority the current contents of the register in the CPU are transferred into a stack.
- The relevant ISR is loaded into RAM
- A flag is set to signal the ISR has begun
flag is reset when ISR has finished - The F-D-E cycle renews as before
What are agile methodologies?
A collection of methodologies which aim to improve the flexibility of software development
What is Immediate addressing?
The operand is the actual value upon which the instruction is to be performed
What is direct addressing?
The operand gives the address which holds the value upon which the instruction is to be performed
What is Indirect addressing?
The operand gives the address of a register that holds another address,
where the data is located.
What is Hashing?
A technique used to store and retrieve data in a table by using a unique key. it is used to speed up searches and comparisons
What is a Relational database?
a relational database is a type of database that stores data in tables, which are related through common fields
What is referential integrity?
Referential integrity is the process of ensuring consistency, as it makes sure that information is not removed if it is required elsewhere in a linked database
What does atomicity (in ACID) mean?
A transaction will be processed completely or not at all
What does consistency (in ACID) mean?
A transaction must maintain referential integrity rules between linked tables
What does Isolation (in ACID) mean?
ensure that each transaction will be isolated and dealt with in a way that does not affect others
What does durability (in ACID) mean?
Once a transaction has been executed it will remain, regardless of the circumstances
What is the PageRank algorithm?
The algorithm used to determine the order used when showing results for a search engine query
Which acts concern the malicious use of computers?
The Computer Misuse Act 1990
Which act protects people’s property online?
The Copyright, Design and patents act 1988
Which act covers the use of personal data?
The data protection act 1998
