Glossary
MC68HC912DG128 — Rev 3.0
Technical Data
MOTOROLA
Glossary
445
input/output (I/O)
— Input/output interfaces between a computer system and the external world.
A CPU reads an input to sense the level of an external signal and writes to an output to
change the level on an external signal.
instructions
— 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) and instruction.
inter-IC bus (I
2
C) — A
two-wire, bidirectional serial bus that provides a simple, efficient method
of data exchange between devices.
interrupt
— A temporary break in the sequential execution of a program to respond to signals
from peripheral devices by executing a subroutine.
interrupt request
— A signal from a peripheral to the CPU intended to cause the CPU to
execute a subroutine.
I/O
— See “input/output (I/0).”
jitter
— Short-term signal instability.
latch
— A circuit that retains the voltage level (logic 1 or logic 0) written to it for as long as power
is applied to the circuit.
latency
— The time lag between instruction completion and data movement.
least significant bit (LSB)
— The rightmost digit of a binary number.
logic 1
— A voltage level approximately equal to the input power voltage (V
DD
).
logic 0
— A voltage level approximately equal to the ground voltage (V
SS
).
low byte
— The least significant eight bits of a word.
M68HC12
— A Motorola family of 16-bit MCUs.
mark/space
— The logic 1/logic 0 convention used in formatting data in serial communication.
mask
— 1. A logic circuit that forces a bit or group of bits to a desired state. 2. A photomask used
in integrated circuit fabrication to transfer an image onto silicon.
MCU
— Microcontroller unit. See “microcontroller.”
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.