Software designer - intermediate, exam summary

Presentation of data

Examination site 1：CPU、 Arithmetic unit 、 The concept of controller

Examination site 2: Hexadecimal conversion

Computer basic unit ：
position （ The bit ）bit b 1B=8b 1 Bytes equal to 8 The bit
byte byte B 1KB=1024 B 1 Kilobytes equals 1024 byte
kilobytes KB

Hexadecimal English letters indicate
Ten （D）、 Two （B）、 8、 ... and （O）、 sixteen （H）

Commonly used binary

Hexadecimal representation after ten

（ Short division ） Stop when the quotient is zero , And the final remainder should be 0, And the remainder should be recorded from bottom to top


Memory programming ladder steps
First step ： Big decrease plus one to get 16 The value of base
The second step ： Convert to decimal ( Unit is B）
The third step ： Convert the unit consistent with the answer except 1024（2 Of 10 Power ）

Examination site 3: Coding system ( Original code / Inverse code / Complement code / Shift the code )
Original code : The highest bit is the sign bit , The remaining low bits represent the absolute value of the value

Inverse code : The inverse of a positive number is the same as the original , The inverse of a negative number is the bitwise negation of its absolute value
( The sign bits remain the same )

Complement code : The complement of a positive number is the same as the original code , The complement of a negative number is the last digit of its inverse plus 1
( The sign bits remain the same )
notes ： The complement of the complement is the original code , Complement and shift positive 0 negative 0 It's all the same

Shift the code : The sign bit of complement is reversed bit by bit

The machine word length is n The range of signed numbers represented by various code systems

Examination site 4: The representation of floating-point numbers




（R It's an order code , Include a level symbol ）.（M It's the mantissa , Including one digit sign ）

Examination site 5: Addressing
1、 Address immediately . The operands are included in the instruction .
characteristic : The operands are directly in the instruction , Fast , Poor flexibility

2、 Direct addressing . The operands are stored in memory units , The instruction directly gives the... Of the storage unit where the operand is located
Address .
characteristic : The instruction stores the address of the operands

3、 Register addressing . The operand is stored in a deposit In the device , Instruction gives the name of the register where the operands are stored .
characteristic : Registers hold operands

4、 Register indirection . The operands are stored in memory units , The address of the storage unit where the operand is located is in a
In the register .
characteristic : The address of the operands is stored in the register

5、 Indirect addressing . The address in the instruction that gives the address of the operand .
characteristic : There is an address in the instruction , This address corresponds to the address of the operands .

The addressing mode is sorted from fast to slow ： Address immediately 、 Register addressing 、 Direct addressing 、 Register indirection 、 Indirect addressing