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application hardware. Examples of
software development tools include text
editors, assemblers, debug monitors, and
simulators. Examples of hardware
development tools include simulators,
logic analyzers, and PROM
programmers. An in-circuit simulator
combines a software simulator with
various hardware interfaces.
—E—
EPROM
Erasable, programmable read-only
memory. A non-volatile type of memory
that can be erased by exposure to an
ultra-violet light source. MCUs that have
EPROM are easily recognized by their
packaging: a quartz window allows
exposure to UV light. If an EPROM
MCU is packaged in an opaque plastic
package, it is termed a
one-time-programmable OTP MCU,
since there is no way to erase and rewrite
the EPROM.
—F—
—G—
—H—
H
Abbreviation for half-carry in the
condition code register of the
MC68HC908AB32. This bit indicates a
carry from the low-order four bits of an
8-bit value to the high-order four bits.
This status indicator is used during BCD
calculations.
M68ICS08ABUM/D
APPENDIX B – GLOSSARY
—I—
I
Abbreviation for interrupt mask bit in the
condition code register of the
MC68HC908AB32.
index register
An 8-bit CPU register in the
MC68HC908AB32 that is used in
indexed addressing mode. The index
register (X) also can be used as a
general-purpose 8-bit register in addition
to the 8-bit accumulator.
input-output (I/O)
Interfaces between a computer system
and the external world. For example, 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
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.
—J—
—K—
—L—
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
B-3
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