MC68HC908AZ60A_13 Datasheet, PDF (408/414 Pages) Freescale Semiconductor, Inc – Microcontrollers

Glossary
high byte — The most significant eight bits of a word.
illegal address — An address not within the memory map
illegal opcode — A nonexistent opcode.
I — The interrupt mask bit in the condition code register of the CPU08. When I is set, all interrupts are
disabled.
index register (H:X) — A 16-bit register in the CPU08. The upper byte of H:X is called H. The lower
byte is called X. In the indexed addressing modes, the CPU uses the contents of H:X to determine the
effective address of the operand. H:X can also serve as a temporary data storage location.
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).”
IRQ — See "external interrupt module (IRQ)."
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.
low voltage inhibit module (LVI) — A module in the M68HC08 Family that monitors power supply
voltage.
LVI — See "low voltage inhibit module (LVI)."
M68HC08 — A Freescale family of 8-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.
mask option — A optional microcontroller feature that the customer chooses to enable or disable.
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
408
Freescale Semiconductor