Glossary
M68HC12A4EVB Evaluation Board — Rev. 1
User’s Manual
MOTOROLA
Glossary
147
instructions — Instructions are operations that a CPU can perform.
Instructions are expressed by programmers as assembly language
mnemonics. A CPU interprets an opcode and its associated operand(s)
as an instruction.
listing — A program listing shows the binary numbers that the CPU needs
alongside the assembly language statements that the programmer
wrote. The listing is generated by an assembler in the process of
translating assembly language source statements into the binary
information that the CPU needs.
LSB — Least significant bit.
MCU – Microcontroller unit — Microcontroller. A complete computer
system including CPU, memory, clock oscillator, and I/O on a single
integrated circuit.
MSB — Most significant bit.
object code file — A text file containing numbers that represent the binary
opcodes and data of a computer program. An object code file can be
used to load binary information into a computer system. Motorola uses
the S-record file format for object code files.
operand — An input value to a logical or mathematical operation.
opcode — A binary code that instructs the CPU to do a specific operation in a
specific way.
OTPROM — A non-volatile type of memory that can be programmed but
cannot be erased. An OTPROM is an EPROM MCU that is packaged in
an opaque plastic package. It is called a one-time-programmable MCU
because there is no way to expose the EPROM to a UV light.
program counter — The CPU register that holds the address of the next
instruction or operand that the CPU will use.
RAM — Random access memory. Any RAM location can be read or written
by the CPU. The contents of a RAM memory location remain valid
until the CPU writes a different value or until power is turned off.
registers — Memory locations that are wired directly into the CPU logic
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Freescale Semiconductor, Inc.
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