Intel 8080 Architecture
Intel 8080 Instruction Set
Overview
The 8080 is an 8 bit processor released by Intel in 1974. Originally designed for use in calculators and other electronic devices it found widespread use in early microcomputers including the Altair 8080, IMSAI 8080 and others using the S-100 bus standard based on the Altair 8080.
The information on this page is based on the Intel 8080/8085 Assembly Language Programming book
Source Line Format
The format of instructions in 8080 assembly is
[Label:] Opcode [Operand[,Operand]] [;Comment]
Label
The label field is used to identify the instruction for use by other instructions and corresponds to the location of that instruction
A label can contain 1 to 6 characters, the first character must be alphabetical or the special characters '?' or '@'. The remaining characters can be alphanumeric
The label is terminated with a colon
Opcode
The opcode field contains the nonmuonic for the instruction or assembler directive
Operands
Operands are arguments to the instruction or directive. If multiple operands are specified then they should be separated by commas
Typically the first operand represents the destination and the second operand specifies the result
Comments
The comment field contains information used to annotate and describe the program. It is preceded by a semicolon and may contain any printable character