Chapter VI and low level programming language pseudo-code
1, computer operations
◆ computer is capable of storing, retrieving and programmable electronic device for processing data
2, machine language
◆ pep / 8 seven registers, focuses on:
program counter (PC ), where the address contains the next instruction to be executed in the
instruction register (IR), which contains a copy of the instruction being executed
accumulator (a register), it is used to store the operating data and results
◆ a byte the maximum can be represented by the decimal number 255, is represented by binary 11111111, is a hexadecimal FF. The maximum number of decimal one word (16-bit) can be represented by 65535, is expressed in binary 1111111111111111, hexadecimal is FFFF.
◆ an instruction consists of two parts, i.e., 8-bit instruction specifier and (optional) 16-bit operand specifier
instruction specifier describes the position and how to interpret what action is to be performed operands
operand specifier is stored operand itself or operand address
◆ instruction format specifier
instruction specifier format of a differ number of bits the specific operation used representing
specifies which register using bit 54-bit operation code
3 bits hunt addressing mode specifier indicates how to parse the operand part of the instruction. Addressing mode is 000, then the number of instructions stored in the instruction symbol is the number of operations, called immediate addressing; addressing mode is 001, then the operator said specifier stored in the memory operand address name is located, said direct addressing.
Some examples of instructions ◆
0000 stops executing
1100 Loading operand register A
1110 A of the contents of register operands stored
0111 operand register A is added to the
value obtained by subtracting the value of the operand register A 1000
01001 character input operand
01010 operations from output character number
3, pseudocode,
pseudocode algorithm is a language expression
◆ pseudocode function
variable
assignment
input / output
select
repeat
Chapter VII of problem solving and algorithm design
1, computer problem solving
(1) analyze the problem: understand the problem, list the information that must be processed, are listed assumptions, develop a comprehensive universal program or algorithm
main task (2) lists
(3 ) the preparation of the remaining modules
(4) is rewritten as needed to rewrite and
2, a simple algorithm parameters
◆ with selection algorithm
algorithm ◆ with cycle
count cycle control: the process can be repeated the specified number of times, the circulating mechanism is the number of simple recording process is repeated and repeated again before the start of the detection cycle has ended or
event-controlled cycle: the cycle is repeated the number of times an event occurs by the controlled circulation within the body of the loop itself is called an event loop control
◆ complex variable
array: An array is homogeneous collection of known items, they can be accessed by a single item in the collection position of the
recording: the recording is known a heterogeneous collection of items, wherein the items can be accessed separately by name.
◆ search algorithm
search order
order ordered array of search
binary search: Find operate in an ordered list of items, most of the search range by comparing exclusions
◆ Sort
Select the sort
bubble sort
insertion sort
◆ recursive algorithm
using the algorithm in a its own time, this algorithm is called recursive algorithm (recursive algorithm is the ability to call itself)
3, several key ideas
◆ information shield: the practice of hidden details of the module to control access to these details of
◆ abstract: complex systems a model that includes only details of the observer must
Data abstraction: the logical view of the data and its practical separating
procedure Abstract: The logical view of the operation and its practical separated
abstraction: the logical view of the control structure and its practical separated
control structures: for changing the normal the statement sequential flow of control of
◆ naming things
◆ test