"SDD" Flashcards
three different types of design methods
rapid application development, agile methodologies, top down design // waterfall
Memory write operation
> the processor sets up the address bus with the register memory address by placing it in MAR
the processor sets up the data bus with the value to be stored in memory by placing it in MDR
CU activates write line on control bus
the address bus opens the relevant memory location at that address
the contents of the memory data register are released and sent along the data bus into the memory location
pre-defined function: random letter lowercase // character
randomletter=int(randrange(97,122)
chr(randomletter)
efficient
ability to solve the problem without using too much memory and processing time
Memory read operation
> the processor sets up the address bus with required memory address by placing in the MAR
CU activates the read line on the control bus
the address bus opens the relevant memory location at that address
the contents of the memory location are released, sent along the data bus and into the MDR
data is then decoded and executed
what is corrective maintenance
fixing the bugs that slipped though the testing stage by updating the section of code containing the error. This is then released as a software patch
Most expensive to cheapest
Registers, USB/Flash Memory,CPU Cache, RAM
Registers, CPU Cache, RAM, USB/Flash Memory
standard algorithm for: counting occurrences (8)
- 1 occurrences = 0
- 2 take in value to find
- 3 for each item
- 4 if current item = value to find then
- 5 occurrences = occurrences + 1
- 6 end if
- 7 next item in list
- 8 display occurrences
IN
By Value
IN/OUT
By Reference
portable
ability of the program to be run on different operating systems
what is module library
contains a set of pre-written and pre-tested subroutines of code that are available to programmers
Largest to smallest capacity
Registers, USB/Flash Memory,CPU Cache, RAM
USB/Flash Memory, RAM, CPU Cache, Registers
an advantage of using agile design methodologies
they should respond to unpredictability and cope with rapid change.
pre-defined function: length
len()
the ____ bus identifies the location
address
7 stages of software development
analysis design implementation testing documentation evaluation maintenance
low level language
represented by 1’s and 0’s. processors only understand these digits. this is known as machine code. harder for us to understand
what is adaptive maintenance
takes into account new conditions such as the customer getting new hardware or software. it updates your software to work under new conditions such as a new operating system
agile methodologies
a repetitive process that increases bit by bit through iterative and incremental development - are able to respond to unpredictability and cope with rapid change
what does the NON-MASK-ABLE INTERRUPT line do
Message from peripheral device causes the processor to stop processing current task. Current data is stored in a temporary area called the stack. The processor deals with the interrupt. The data is then retrieved from the stack and the task is resumed. This cannot be ignored or prevented.
(used to indicate that an interrupt to the fetch/execute cycle is taking place that cannot be ignored)
what are dry runs / trace tables in systematic testing
a mental run of the program where the programmer examines the code one step at a time
an execution error is when
the program crashes due to unexpected input whilst it was running
ascii (#bits)
(7bits) 2^7=128
how to get binary for negative number
find the binary representation
flip the bits (turn the 1’s into 0’s and vice versa)
add 1
systematic testing involves
going through a progression from testing the subroutines and working your way up to testing the entire system. The sort of testing is planned in advance and followed in a logical order.
Fastest to slowest
Registers, USB/Flash Memory,CPU Cache, RAM
Registers, CPU Cache, RAM, USB/Flash Memory
what does the RESET line do
resets the computer to its initial switch on state
binary addition rules
0+0=0
1+0=1
0+1=1
1+1=1 0 (2)
what does the INTERRUPT line do
Message from peripheral device causes the processor to stop processing current task. Current data is stored in a temporary area called the stack. The processor deals with the interrupt. The data is then retrieved from the stack and the task is resumed.
(used to indicate that an interrupt to the fetch/execute cycle is taking place)
a procedural program has
a clear start and endpoint and follows through the path to give solution
three different types of programming languages
procedural, object orientated, declarative
storing video depends on the:
length / time (seconds)
frame rate (fps)
bit depth (bits)
number of pixels in one frame (pixels)
high level language
is similar to human languages easier to understand and spot errors and is more readable
standard algorithm for: finding max (7)
- 1 max value = first item in list
- 2 for each item in list
- 3 if next item > max value then
- 4 max value = next item
- 5 end if
- 6 next item in list
- 7 display max value
what is the implementation stage
writing or implementing the code using a particular programming language
colours = [number]
colour depth = ?
log₂(number)
By Val is when
a value is passed into a procedure but isn’t passed out.
7 stages of software development
analysis, design, implementation, testing, documentation, evaluation, maintenance
a syntax error is when
the program crashes as a result of incorrectly written code.
audio =
length/time x sampling freq. x no. channels x sampling depth
standard algorithm for: finding min (7)
- 1 min value = first item in list
- 2 for each item in list
- 3 if next item < min value then
- 4 min value = next item
- 5 end if
- 6 next item in list
- 7 display min value
a object orientated program involves
“creating” specific ‘objects’ and all objects are represented by classes and a set of objects can perform tasks.
a cache
is a hardware or software component that stores data so that future requests for that data can be served faster
robust
ability to cope with errors when the program is running
maintainable
ability for the program to have alterations and updates made at a later date
a declarative program has
a collection of facts and rules that describe the problem. a query is entered and a solution is provided
unicode (#bits)
(16bits) 2^16=65536
what is a local variable
a variable that is used within a single block of code and cannot be seen or accessed from other parts of the program
rapid application development
minimal planning in favour of rapid prototyping
an advantage of using rapid application development
allows software to be written much faster and it makes it easier to change requirements
top down design / waterfall
the problem at the top is worked downwards into smaller manageable problems
advantage of a module library
don’t have to rewrite code to problems and they have already been checked for errors so are error free.
what is a global variable
a variable that is created with the main part of the program and can be seen and accessed from all parts of the program
what does the READ line do
informs memory data is to be sent to the processor from specific memory location
what is the scope of a variable
it defines which part of the program can see the variable and change its value
what does the WRITE line do
informs memory data is to be stored in a specific memory location
standard algorithm for: input validation (5)
- 1 ask user for input
- 2 do while data is invalid
- 3 ask user to re-enter data
- 4 user re-enters data
- 5 loop
what are breakpoints in systematic testing
when the programmers program the program to stop at scheduled intervals in the program so that the status of the program can be examined in stages in the program
By Reference is when
a value is passed in and changed then gets passed out again.
a logic error is when
the program is executed fully but with unexpected output
what is perfective maintenance
updates being made to the software that add new features to the software.
what does the CLOCK line do
generates a constant pulse which regulates flow of information (dictates the pace of the fetch/execute cycle)
comprehensive testing involves
the process of testing normal, exceptional and extreme data.
increasing the exponent increases the _________ of decimal numbers that can be represented
range
each line for the control bus has _______
a different purpose
reliable
ability to work correctly if the correct data is entered
video =
length/time x frame rate x bit depth x num. px in one frame
pre-defined function: string
str()
storing audio depends on the:
length / time (seconds)
sampling freq. (Hz)
number of channels (mono/stereo)
sampling depth (bits)
standard algorithm for: linear search (9)
- 1 ask user for value to find
- 2 take in value to find
- 3 found = false
- 4 do
- 5 if current item = value to find then
- 6 found = true
- 7 position = current item position in list
- 8 end if
- 9 loop until (found=true) or (end of list)
increasing the mantissa increases the _________ of decimal numbers that can be represented
accuracy
readable
ability of the program to be understood by another programmer
advantages of using dry runs and trace tables
- see what the code will do before you run it
- spot errors in the code
extended ascii (#bits)
(8bits) 2^8=256
Declarative Language: Line 1 human(einstein). Line 2 human(pascal). Line 3 human(lovelace). Line 4 mortal(X):-human(X). State the feature being used in line 4 and explain a benefit of its use
Adds information/meaning based on other facts/rules or Reduces need for repetition of facts/rules or improves efficiency by reducing code or Facilitates queries or Use of variables allow values to be returned
symptoms of a DOS attack
slow performance and inability to access data. bandwidth consumption, resource starvation
effects / costs of a DOS attack
disruption to users and businesses and lost revenue, labour in rectifying fault
Explain the difference between a public key and a private key when securing the transmission of data.
A public key is used to encrypt the personal data. A private key is used to decrypt the personal data.
Name and describe a feature of a declarative language.
Rules; Use variables which can be applied to existing fact/rules. Pattern; allows facts/rules to be matched.
Advantages of using a public cloud
Public cloud services can be easily increased or decreased to match current needs.
Can set up or easily expand capacity of public cloud storage without the company purchasing hardware.
Public cloud removes need for backup/maintenance/ administration strategies the company
Public cloud has lower initial costs than private cloud.
State two precautions used to ensure security of data on public cloud storage.
Username and passwords to access public cloud.
Use of encryption.
Firewall.
Require use of digital certificate
Describe how interframe compression is also used to reduce the file size of the video.
Key frames/I-frames are stored and saves changes between (key) frames.
Explain how Run Length Encoding would compress this image.
Stores the colour of a pixel and the number of repetitions of that colour.
The developers of the app are using agile methodologies. They employ usability testing as part of this. Describe how usability testing influences the development of the app. (3)
Create prototypes/wireframes/ design of user interface.
Prospective users perform tasks.
Developers observe/interview/ discuss scenarios with users.
Obtain feedback to influence changes.
What are personas and test cases for wdd
Personas: a type of user with a specific age and experience Test cases: a set of actions to verify a particular feature or function
