Special Terminology - Intel Embedded Intel486 Hardware Reference Manual

EMBEDDED Intel486™ PROCESSOR HARDWARE REFERENCE MANUAL
Register Bits
Register Names
Signal Names
1.3

SPECIAL TERMINOLOGY

The following terms have special meanings in this manual.
Assert and Deassert
DOS I/O Address
Expanded I/O Address
PC/AT Address
Set and Clear
1-4
When the text refers to more that one bit, the range of bits is represented
by the highest and lowest numbered bits, separated by a long dash
(example: A15–A8). The first bit shown (15 in the example) is the most-
significant bit and the second bit shown (8) is the least-significant bit.
Register names are shown in uppercase. If a register name contains a
lowercase italic character, it represents more than one register. For
example, PnCFG represents three registers: P1CFG, P2CFG, and P3CFG.
Signal names are shown in uppercase. When several signals share a
common name, an individual signal is represented by the signal name
followed by a number, while the group is represented by the signal name
followed by a variable (n). For example, the lower chip-select signals are
named CS0#, CS1#, CS2#, and so on; they are collectively called CSn#.
A pound symbol (#) appended to a signal name identifies an active-low
signal. Port pins are represented by the port abbreviation, a period, and
the pin number (e.g., P1.0, P1.1).
The terms assert and deassert refer to the acts of making a signal
active and inactive, respectively. The active polarity (high/low) is
defined by the signal name. Active-low signals are designated by the
pound symbol (#) suffix; active-high signals have no suffix. To
assert RD# is to drive it low; to assert HOLD is to drive it high; to
deassert RD# is to drive it high; to deassert HOLD is to drive it low.
Peripherals that are compatible with PC/AT system architecture can
be mapped into DOS (or PC/AT) addresses 0H–03FFH. In this
manual, the terms DOS address and PC/AT address are synonymous.
All peripheral registers reside at I/O addresses 0F000H–0FFFFH.
PC/AT-compatible integrated peripherals can also be mapped into
DOS (or PC/AT) address space (0H–03FFH).
Integrated peripherals that are compatible with PC/AT system
architecture can be mapped into PC/AT (or DOS) addresses 0H–
03FFH. In this manual, the terms DOS address and PC/AT address
are synonymous.
The terms set and clear refer to the value of a bit or the act of giving
it a value. If a bit is set, its value is "1"; setting a bit gives it a "1"
value. If a bit is clear, its value is "0"; clearing a bit gives it a "0"
value.