This type of registers offer convenient temporary storage for any type of data and are used for arithmetic operations, this can uniquely address them as one-word or as one-byte portion.
General-Purpose Registers
These register are also considered as the “workhorses” of the system.
General-Purpose Registers
Used for input, output, and arithmetic operations.
AX register
It is sometimes called as the accumulator.
AX register
Used as an index to extend addressing and is also used for computation.
BX register
Also known as base register.
BX register
This is used with certain instructions that perform operations repeatedly. It contains a value to control the number of times a loop is repeated. May also be used for computations.
CX register
Also refered to as the counter register.
CX register
This is used to hold data for any purposes such as input/output operations, or multiply/divide operations that involve large values.
DX register
Also known as the data register.
DX register
This 16-bit register facilitates referencing parameters that the data and address program passes through the stack.
BP register
Also known as Base Pointer.
BP register
This register indicates the current instruction within the currently executing code segment. It also contains the offset address of the next instruction that is to execute.
IP register
__ stands for Intruction Pointer.
IP register
This register refers to the current word being processed in the stack. Also provides an offset value.
SP register
Both the __ and __ registers are associated with the SS register and permit the system to access data in the stack segment.
SP and BP
May be referred to as Stack Pointer.
SP register
These registers provide for addressing an area of memory known as the current segment.
Segment Registers
It contains data and return addresses of procedures or subroutines. It is implemented as a 'stack' data structure.
Stack Segment
This register contains the starting address of a program's code segment.
CS Register
The segment address plus an offset values in the IP register indicates the address of an instruction to be fetched for execution.
CS Register
Also referred to as Code Segment.
CS Register
This register instructs the use of address to locate data.
DS Register
It also contains the starting address of a program's data segment.
DS Register
DS stands for Data Segment.
DS Register
This register is associated with the DI register, that a program requires and initialize it with an appropriate segment address.
ES Register
Used by some string operations to handle memory addressing.
ES Register
__ stands for Extra Segment.
ES Register
Permits the implementation of a stack in memory that a program uses for temporary storage of addresses and data.
SS Register
The system stores the starting address of a program's stack segment in the ________.
SS Register
Stands for Stack Segment.
SS Register
These are registers available for indexed addressing and addition/subtraction operations.
Index Registers
Associated with the DS register which is required for some string operations.
SI Register
Also referred to as String Index.
SI Register
Associated with the ES register which is also required for some string operations.
DI Register
Also referred to as Destination Index.
DI Register
These are special registers that indicate the present status of the computer and the results of processing.
Flag Registers
Many instructions involving comparison and arithmetic change the status of the flags, which some instructions may test to determine subsequent actions.
Flag Registers
This register indicates the result of an operation if it is too long to be stored in the destination operand.
Overflow Flag(OF)
__ dislayed if there is an OVERFLOW; and __ is displayed for NO OVERFLOW.
OV , NV
This register is used in string operations to determine the direction of data transfer.
Direction Flag(DF)
__ is displayed for UPWARD direction; otherwise __ is displayed for DOWNWARD.
UP , DN
Indicates that all external interrupts such as keyboard entries are to be processed or ignored.
Interrupt Flag (IF)
__ is displayed for ENABLED INTERRUPT; and __ for DISABLED INTERRUPT.
EI , DI
Indicates that the result of an operation is positive or negative.
Sign Flag(SF)
__ is diplayed for PLUS; and __ for NEGATIVE.
PL , NG
Indicates whether the an operation produced a zero result.
Zero Flag (ZF)
__ is diplayed for ZERO and __ for NON-ZERO.
ZR , NZ
This register is similar to carry flag xcept that it indicates the presence or absence of a carry or borrow based on 4-bit numeric representation in bits 0, 1, 2, and 3.
Auxiliary Flag (AF)
__ is displayed for NO AUXILIARY CARRY; and __ for AUXILIARY CARRY.
NA , AC
Indicated whether the result of an operation contains an even or odd number of 1's.
Parity Flag (PF)
__ is displayed for PARITY EVEN; and __ for PARITY ODD.
PE , PO
This register indicates whether the instuctions produced a value that can be too big (or too small) to be held in the specifeid register or memory location.
Carry Flag (CF)
__ is displayed for CARRY; and __ for NO CARRY.
CY , NC
A software that is classified as a debugger, which is used for testing and debugging programs.
Debug
Display all program code and data in hexadecimal form. Any data that the user enters into memory must also be in hex form.
Debug
Provides a single-step mode, which allows you to execute a program one instruction at a time so that you can view the effect of each instruction on memory locations and registers.
Debug
Advantages of Debug
It is simple to use
It requires relatively little memory
Provide a controlled testing environment so you can monitor and control the execution of a program.
DOS Debug.COM
It may be used to load, alter, or display any file.
DOS Debug.COM
(T/F) They are not case-sensitive. They assume that all numbers given are in hexadecimal format. You can enter a space only when it is needed to separate parameters of a particular command.You should specify segments and offset with a colon, in the form of <segment>: <offset>.
