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MC68HC08AZ60 Datasheet, PDF (441/452 Pages) Motorola, Inc – Advance Information | |||
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Freescale Semiconductor, Inc.
Glossary
external interrupt module (IRQ) â A module in the M68HC08 Family with both dedicated
external interrupt pins and port pins that can be enabled as interrupt pins.
fetch â To copy data from a memory location into the accumulator.
firmware â Instructions and data programmed into nonvolatile memory.
free-running counter â A device that counts from zero to a predetermined number, then rolls
over to zero and begins counting again.
full-duplex transmission â Communication on a channel in which data can be sent and
received simultaneously.
H â The upper byte of the 16-bit index register (H:X) in the CPU08.
H â The half-carry bit in the condition code register of the CPU08. This bit indicates a carry from
the low-order four bits of the accumulator value to the high-order four bits. The half-carry
bit is required for binary-coded decimal arithmetic operations. The decimal adjust
accumulator (DAA) instruction uses the state of the H and C bits to determine the
appropriate correction factor.
hexadecimal â Base 16 numbering system that uses the digits 0 through 9 and the letters A
through F.
high byte â The most significant eight bits of a word.
illegal address â An address not within the memory map
illegal opcode â A nonexistent opcode.
I â The interrupt mask bit in the condition code register of the CPU08. When I is set, all interrupts
are disabled.
index register (H:X) â 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) â 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.
MOTOROLA
MC68HC08AZ60 â Rev 1.0
Glossary
441
For More Information On This Product,
Go to: www.freescale.com
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