Intel 64 and IA-32 Architectures Software Developers Manual Volume 1, Basic Architecture

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For example:
LOADREG: MOV EAX, SUBTOTAL
In this example, LOADREG is a label, MOV is the mnemonic identifier of an opcode,
EAX is the destination operand, and SUBTOTAL is the source operand. Some
assembly languages put the source and destination in reverse order.
1.3.3 Hexadecimal and Binary Numbers
Base 16 (hexadecimal) numbers are represented by a string of hexadecimal digits
followed by the character H (for example, 0F82EH). A hexadecimal digit is a char-
acter from the following set: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F.
Base 2 (binary) numbers are represented by a string of 1s and 0s, sometimes
followed by the character B (for example, 1010B). The “B” designation is only used in
situations where confusion as to the type of number might arise.
1.3.4 Segmented Addressing
The processor uses byte addressing. This means memory is organized and accessed
as a sequence of bytes. Whether one or more bytes are being accessed, a byte
address is used to locate the byte or bytes memory. The range of memory that can
be addressed is called an address space.
The processor also supports segmented addressing. This is a form of addressing
where a program may have many independent address spaces, called segments.
For example, a program can keep its code (instructions) and stack in separate
segments. Code addresses would always refer to the code space, and stack
addresses would always refer to the stack space. The following notation is used to
specify a byte address within a segment:
Segment-register:Byte-address
For example, the following segment address identifies the byte at address FF79H in
the segment pointed by the DS register:
DS:FF79H
The following segment address identifies an instruction address in the code segment.
The CS register points to the code segment and the EIP register contains the address
of the instruction.
CS:EIP