Assembler Directives, Interrupts Flashcards
It controls the assembly process.
assembler directives
It indicates how an operand or section of a program is to be processed by the assembler.
directives
These are designed to create the required data and perform all appropriate memory allocation and data formatting for little – endian values.
assembler directives
These are set of instructions to answer a specific problem.
program
A specific directive that can be used to assign a value to a constant variable.
define
indicates the start of the segment and its symbolic name
segment
indicate the end of the segment
ends
used for memory reservation, the assembler stores a zero into locations specified by this
?
A specific directive that creates an array.
dup
A specific directive that repeats an expression a given number of times.
dup
A directive that forces the assembler to align the next segment at an address divisible by specified divisor.
align
Used to start the data segment on word boundary
align 2
Used to start the data segment on doubleword boundary
align 4
A specific directive that is used to give a name to some value or symbol.
equ
assign either a byte or a word address to a label
this
A specific derivative that changes the starting offset address of the data in the data segment.
org
A specific directive that is similar to an alias of a segment.
assume
A specific directive that tells the assembler what names have been chosen for the segments.
assume
A specific directive that indicates the start of the procedure
proc
A specific directive that indicates the end of the procedure
endp
A procedure that resides in the same code segment as the program (local).
near (procedure)
A procedure that may reside at any location in the memory system (global).
far (procedure)
A specific directive that indicates which registers are used by the procedure.
uses
A specific derivative that initializes memory model before defining any segment
.model
Requires that all software and data fit into one 64K-byte memory segment, useful for many small programs
tiny (model)
Requires that only one data segment be used with one code segment, for a total of 128K-bytes of memory.
small (model)
A specific derivative that returns to DOS but error code is not defined.
.exit
A specific derivative that returns to DOS with an error code 0.
.exit 0
A specific directive that temporarily suspends execution of the main program.
interrupts
An interrupt that generated by changing the logic levels of either the processor’s hardware interrupt inputs.
External Hardware Interrupts
An interrupt that cannot be ignored by the CPU.
Nonmaskable interrupt (NMI)
An interrupt that can be enabled or disabled by the state of the interrupt.
interrupt request (INTR/IRQ)
An interrupt that is generated directly by an executing program
Internal software interrupts (exceptions)
These are instructions executed during the normal program flow.
INT
INTO (Interrupt on Overflow)
It happens when division by zero is detected in the execution unit
DIV
IDIV
The lowest priority interrupt.
single-step
The highest priority interrupt.
Divide by zero (Divide - error)
Interrupt Priority
Divide - error
INT, INTO
NMI
INTR
single-step
A dedicated table in memory used for storage of their interrupt service routine (ISR) starting address.
Interrupt Vector Table
In protected mode, an _____________________ that uses 8-byte descriptors to describe each of the interrupts replaces the vector table.
interrupt descriptor table
A program that tells the processor what to do when the interrupt occurs.
Interrupt service request
