MC68HC912BD32 Datasheet, PDF (285/292 Pages) Freescale Semiconductor, Inc – Advance Information

Freescale Semiconductor, Inc.
Glossary
index registers (IX and IY) — Two 16-bit registers in the CPU. In the indexed addressing
modes, the CPU uses the contents of IX or IY to determine the effective address of the
operand. IX and IY can also serve as a temporary data storage locations.
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.
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.”
Glossary
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MC68HC912BD32 Rev 1.0