A251 User's Guide

Numbers

Numbers may be specified in hexadecimal (base 16), decimal (base 10), octal (base 8), and binary (base 2). The default representation is decimal. A decimal, octal, or binary number's first character must always be a digit (0-9). Hexadecimal numbers whose first character is not a digit (0-9) must be prefixed with a zero ('0'). The following table illustrates various types of numbers:

Note

• Hexadecimal numbers may be written using C notation. For example, 0x12AB.
• Hexadecimal numbers must begin with a 0 if the first digit is A-F.
• The dollar sign character ('$') may be used in numbers to make them more readable (as long it is not the first or last character). For example:

  1111$0000$1010$0011B   - is equivalent to -   1111000010100011B
  1$2$3$4                - is equivalent to -   1234
  

Colon Notation for Numbers

The A251 assembler supports the notation page:number for specifying absolute addresses. Numbers specified with this notation receive the memory type EDATA when page is 0 or ECODE for all other pages. In this way, you can use such numbers for referencing any memory location. For example:

ABSVAL1  EQU   0:20H       ; symbol to address location 20H
ABSVAL2  EQU   0:80H       ; symbol to address location 80H in EDATA space
PORT0    EQU   S:80H       ; symbol to SFR space 80H
ENTRY    EQU   10:2000H    ; entry point at location 102000H

         MOV   WR0,ABSVAL1
         MOV   R1,ABSVAL2
         MOV   PORT0,R1
         EJMP  ENTRY
         MOV   WR0,0:20H    ; access to ABSVAL1
         MOV   R1,0:80H     ; access to ABSVAL2
         MOV   S:80H,R1
         EJMP  10:2000H

The colon notation is accepted in several A251 controls and is converted as described.

Note

• The colon notation is provided for source compatibility with other 251 macro assemblers. If you do not need to port your code to other assemblers, it is recommended that you use the replacement sequence in your assembler source file.