AP: Application Processor, any x86 processor other than the Bootstrap Processor on IA-32 SMP systems
ACPI: Advanced Configuration and Power Interface
APIC: Advanced Programmable Interrupt Controller
APM: Advanced Power Management, a BIOS-managed power management specification for personal computers
BSP: Bootstrap Processor, the primary booting processor on IA-32 SMP systems
BSS: Block Started by Symbol: the uninitialized data segment
BKL: Big Kernel Lock, the Linux global kernel lock
CRn: Control Register n, i386-specific control registers
FPU: Floating Point Unit, a separate math coprocessor device
GB: gigabyte (1024 * 1024 * 1024 bytes)
GDT: Global Descriptor Table, an i386 memory management table
IA: Intel Architecture (also i386, x86)
IDT: Interrupt Descriptor Table, an i386-specific table that contains information used in handling interrupts
initrd: initial RAM disk (see "linux/Documentation/initrd.txt")
IPC: Inter-Process Communication
IPI: Inter-processor Interrupt, a method of signaling interrupts between multiple processors on an SMP system
IRDA: InfraRed Data Association
IRQ: Interrupt ReQuest
ISA: Industry Standard Architecture
KB: kilobyte (1024 bytes)
LDT: Local Descriptor Table, an i386-specific memory management table that is used to describe memory for each non-kernel process
MB: megabyte (1024 * 1024 bytes)
MCA: Micro Channel Architecture, used in IBM PS/2 computers
MP: Multi-processor
MSW: Machine Status Word
MTRR: Memory Type Range Registers
PAE: Physical Address Extension: extends the address space to 64 GB instead of 4 GB
PCI: Peripheral Component Interconnect, an industry standard for connecting devices on a local bus in a computer system
PCMCIA: Personal Computer Memory Card International Association; defines standards for PCMCIA cards and CardBus PC Cards
PIC: Programmable Interrupt Controller
PNP: Plug aNd Play
PSE: Page Size Extension: allows 4 MB pages
SMP: Symmetric Multi Processor/Processing
TLB: Translation Lookaside Buffer, i386-specific processor cache of recent page directory and page table entries
TSS: Task State Segment, an i386-specific task data structure
UP: Uniprocessor (single CPU) system.