UML Diagrams: Sequence and Class Diagrams
Sequence Diagram
This tool is part of the UML diagrams and allows dynamic plot the sequence of steps or activities that are run on a particular use case. Elements are:
- Objects: Represented by a rectangle with the name at the bottom, a broken line which we call lifeline. On this is placed a vertical rectangle which call activities which indicates when an object is in operation.
- Messages: Represent information sent from the lifeline of an object to the lifeline of another. They can be of three different
Understanding Link Layer Networks: Protocols, Components, and Configurations
Chapter 9: Link Layer Networks
- What is the role and responsibility of the Level 2 Link Layer Network?
- What are the components addressed by the link layer so that it develops its responsibilities?
- What are the 3 types of configuration that a link can be implemented?
- What are the differences between the IP address and MAC address (Media Access Control)?
- In which part of the network protocol is Ethernet used?
- What were the reasons for the success of the Ethernet protocol compared to its competitors: Token
Binary Representation, Matrices, Algorithms, and Sorting
Binary Repartition
Binary Representation:
- Signed Magnitude: The first bit determines if the number is negative (the sign bit). The rest of the bits represent the magnitude (mantissa).
- One’s Complement: Similar to signed magnitude, but if the number is negative, all bits in the magnitude are inverted.
- Two’s Complement: Similar to one’s complement, but 1 is added to the inverted magnitude if the number is negative.
- Biased Representation: Similar to signed magnitude, but a bias is added to the target number.
C++ Operator Overloading and Polymorphism
Member Operators
Member operators are functions that define the behavior of operators when used with a class’s objects.
- Unary: One operand. Examples:
++i,--i,+value,-value. Declaration:return_type operator ++/--() - Binary: Two operands. Examples:
=,+=,-,*,/,==,&&. Declaration:return_type operator symbol (type [identifier]) - Ternary: Three operands. Example:
condition ? expression1 : expression2
Operators can be overloaded as:
- Member operators: Defined within the class, with access to
Assembly Code Examples: Periodic Interrupts and Keypad Access
Example 1: Periodic Interrupt and Counter
This program demonstrates a periodic interrupt that increments a counter (0 to 99) and prints its value to the text display.
JMP boot
JMP isr
stackTop EQU 0xFF
txtDisplayTens EQU 0x2E0
txtDisplayUnits EQU 0x2E1
counter: ; the counter
DW 0
boot:
MOV SP, stackTop ; Set SP
MOV A, 2 ; Set bit 1 of IRQMASK
OUT 0 ; Unmask timer IRQ
MOV A, 0x20 ; Set timer preload
OUT 3
STI
HLT
isr:
PUSH A
PUSH B
PUSH C
MOV A, [counter] ; Increment the
INC A ; counter
Oracle SQL and PL/SQL Quick Reference
UPPER() lower() InitCap() LENGTH() ROUND(num, 2) TRUNC(num,2)
SUBS/TR(string, initial (pos: from left, neg: from right), length (optional))
INSTR(string, lookup (case sensitive), starting pos, nth occurrence (optional))
LPAD(string, total length, fill), RPAD(string, total length, fill character)
REPLACE(‘original’, ‘find’, ‘replace’), TRIM(whattotrim FROM string)
MOD(number, divisor) -> return remainder
MONTHS_BETWEEN(date, date), ADD_MONTHS(date, # of months to add)
NEXT_DAY(date, ‘FRIDAY’)
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