A character in RAMM assembly language is a printed alphabetic capital letter A through Z, a numeral 0 through 9, or the special characters +, -, and blank. The term alphanumeric character includes both alphabetic and numeric characters and no others. The lowercase b will be used to indicate a blank when it is desirable to call attention to a blank in this presentation of the RAMM assembly language. The RAMM Assembler does not, however, recognize the lowercase b. Blanks will also be indicated by blanks where it is not likely to cause confusion. The term first character refers to the leftmost character of a string of characters.

A RAMM symbol is composed of up to four characters left justified in a field. The first character must be alphabetic; the remaining, alphanumeric. A blank terminates a symbol. Left justified means that the leftmost character in the field appears in the leftmost column of the field. Any blank characters in the field will be at the right side of the field. The following are examples of RAMM symbols:

A constant in RAMM is one of the following:

1. A nonnegative decimal integer containing exactly four decimal digits. All leading zeros must appear. The largest nonnegative value is 9899. A nonnegative constant must be unsigned.
   
   
2. A negative decimal integer that begins with a minus sign followed by exactly three decimal digits. The smallest negative value is -999.

A blank is used in RAMM as a delimiter to terminate a symbol or a constant and to separate fields.

An instruction in RAMM assembly language has the form:

In an instruction, the operation code, OP, tells what action is to take place. Operation codes are defined by the designers of the language and are usually mnemonic (memory aided) abbreviations of the operations to be performed. R is the operand of the instruction and tells what information is to be used in performing the operation. In many instructions it is the symbol that represents the address of a word to be used. A list of RAMM operation codes (op codes) is given elsewhere.

There are two types of instructions in an assembly language: computer instructions and pseudo-instructions (often called pseudo-operations). In a computer instruction, the operation code corresponds to a machine language operation code of the computer. For a computer instruction, the assembler translates a mnemonic OP into a machine language code. Similarly, a symbolic R is translated into the numeric equivalent (an address between 00 and 99, inclusive) that the assembler has assigned to it. The assembler then forms from these parts the numeric machine instruction that corresponds to the symbolic computer instruction written by the programmer.

The second type of assembler language instruction, the pseudo-instruction, furnishes information to the assembler and does not correspond to a numeric machine instruction. From the pseudo-instruction, the assembler determines some kind of action that the assembler is to take with respect to the program that it is translating. A pseudo-instruction may, for example, instruct the assembler that a certain number of consecutive memory locations are allocated with the first one named by a symbol, or that the assembler has reached the end of the program and hence is to stop translating.

Statements are the "sentences" of the assembly language. The most common form of statement contains an instruction consisting of an operation code and its operand (usually a symbol for an address). It also contains, at least implicitly, the address of the memory location in which the instruction is to be stored, and remarks by the programmer. All of this must be presented to the computer in a standard form, which will now be discussed.

The programmer enters the consecutive statements for his program, one per line, in a text file. In many assembly languages (including RAMM), certain parts of a statement must be placed in specific columns in the line. The consecutive columns reserved for some specific use are collectively called a field. A given field is usually identified according to the type of information to be placed in that field, for example, "the OP code field." If information must be located within a field so that the leftmost character occurs in the leftmost column of the field, it is said that the contents of the field must be left justified. Similarly, if the rightmost character must occur in the rightmost column, it is said that the contents of the field must be right justified. All symbols, op codes and constants in RAMM assembly language are left justified in the fields in which they appear.

The RAMM Assembly language statement is composed of six fields: location, operation code, address, sign, number, and remarks. Depending on the operation code, one or more of these fields may be blank.

• The location field (columns 1-4) may contain blanks or a valid RAMM symbol: up to four alphanumeric characters, left-justified, with no imbedded blanks.

• The operation code field (columns 7-9) may contain a valid three- character operation code.

• The address field (columns 11-14) may contain:

• The sign field (column 15) may contain a +, -, or blank. This field is used to allow addressing relative to a given symbol that appears in a location field.

• The number field (column 16) can be blank or contain an integer between 0 and 9, inclusive. This field is used to address a memory location relative to the one identified by the symbol in the location field.

• The remarks field (columns 20 through 40) is completely ignored by the assembler (except in producing a listing). This field may contain any alphanumeric or special character.