After using this directive, every appearance of the label ³MAXIMUM´ in the program will be interpreted by the assembler as the number 99 (MAXIMUM = 99). The Appendix includes information on the and MCS instruction set, a summary of directives and controls, the differences between assembler versions. ASSUME Directive. -. The ASSUME directive is used to tell the assembler that the name of the logical segment should be used for a specified segment.

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A discussion of signed numbers is given in Chapter 6. In other words it cannot be a number. Can be useful for strings, which contain a single quote such as “O’Really”. The END directive is the last line of an program, meaning that in the source code anything after the END directive is ignored by the assembler. It is 8 bits, and the size of each register is also 8 bits. The names used for labels in Assembly language programming consist of alphabetic letters in both uppercase and lowercase, the digits 0 through 9, and the special characters question mark?

EQU is used to define a constant without occupying a memory location. The first character of the label must be an alphabetic character.


These reserve words are the mnemonics for the instructions e. What is the advantage of using EQU? DB is also used to allocate memory in byte-sized chunks.

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This is used to define a constant without occupying a memory location.

Here uses EQU for the counter constant ans then the constant is used to load the R4 register. END directive pseudocode is very important. Some assemblers use “. Assume that there is a constant a fixed value used in many different places in the program, and the programmer wants to change its value throughout.

The number that comes after ORG can be either in hex or in decimal. Facebook Like For Iamtechnical. Off END directive is the last line of an directivex. The ORG directive is used to indicate the beginning of the address.

Explain assembler directives.

For decimal, the “D” after the decimal number is optional, but using “B” [binary] and “H” [hexadecimal] is required. Every assembler has some reserved words which must not be used as labels in the program. By the use of EQU, a programmer can change all valves at once and the assembler will change all of it occurrences, rather than search the entire program and to change the value one by one to fine every occurrence, just change the constant value followed by EQU results changing the all occurrences at once.

This indicates to the assembler the end of the source directievs file. It is the job of the programmer to break down data larger than 8 bits 00 to FFH, or 0 to in decimal to be processed by the CPU. By choosing label names that are meaningful, a programmer can make a program much easier to read and maintain. Like us on Facebook.

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The EQU directive does not set aside storage for a data item but associates a constant value with a data label so that when the label appears in the program, itp constant assembleer will be substituted for the label.

The job of the programmer is to break down data larger than 8 bits [00 to FFH, or 0 to in decimal] to be processed by the CPU. The names used for labels in assembly language programming consists of alphabetic letters in both upper and lower case, the digits 0 through 9, and the special characters question mark [?

Following are some DB examples: First, each label name must be unique. If the number is not followed by ‘H’, it is decimal and the assembler will convert it into hex. Check your rirectives for the list of reserved words.

Labels in Assembly Language Programming and its Rules: Some assembler uses “. The following are some more widely used directives of the The data type used by the can be positive or negative. The microcontroller has only one data type.

It is used to define the 8-bit data.