chapter 4 - processor fundamentls Flashcards
control unit (CU)
controls data flow through the processor and computer system, and synchronises the F-D-E cycles with control signals
arithmetic logic unit (ALU)
responsible for arithmetic, logic or shift processing that may be needed when a program is running
clock speed
number of cycles CPU can execute per second
bus width
number of wires/lines per bus
registers
storage components which have very short access time because of their proximity to the ALU
special-purpose registers
registers with a dedicated function
general-purpose registers
registers used to temporarily store results to access and re-use in subsequent calculations. if there is only one, it is called the accumulator.
current instruction register (CIR)
stores the current instruction while it is decoded and executed
index register (IX)
used to modify operand addresses for index addressing when an immediate constant is added to register contents to form operand addresses
memory address register (MAR)
stores data read from or about to be written to memory. acts as a buffer to the processor
program counter (PC)
stores address of next instruction to be read from
status register (SR)
interpreted as individual bits/flags which are set depending on an event or condition
immediate access store (IAS)
used by CPU to store data awaiting processing so it is instantly accessible. held temporarily and used for frequently accessed data
bus
a parallel transmission component where each wire carries a single bit
address bus
carries an address to the memory controller to identify a location in memory which is to be read/written to. unidirectional
data bus
carries data in use by processor. bidirectional
control bus
used to minimise communication lines by transmitting signals from the control unit. used to synchronise the F-D-E cycle. can be both bidirectional and unidirectional
clock
generates timing signals to synchronise events in the processor and the F-D-E cycle. sends a number of regular pulses in a given time interval
universal serial bus (USB)
industry standard, which allows automatic device configuration and driver installation
video graphics array (VGA)
a video display controller that relays data from a computer to an output device e.g. monitors, projectors, TVs
high definition multimedia interface (HDMI)
a proprietary audio/video interface for transmitting uncompressed video data or uncompressed/compressed digital audio data from a HDMI source device, such as a display controller, monitor, video projector, digital TV or audio device
interrupt
a signal from a device or program that requires processor attention. may have different priorities
immediate addressing
the value used for addressing is in the instruction
direct addressing
an address which holds the value is used in the instruction
indirect addressing
an address which holds the address which holds the value is used in the instruction. the operand is an intermediate location
indexed addressing
the data to the ACC is offset by a base address. the value in the index register is added onto the address in the instruction
relative addressing
the operand is the offset from the current address where the value is stored
instruction set
a set of statements understood by the processor. groups include data movement, arithmetic operations, jump instructions, compare instructions and modes of addressing
linker
a computer program responsible for including links from other files and placing them in a single executable file, library file or object file
loaders
responsible for loading programs and libraries into memory for use and preparing for execution
directives
information the assembler needs to translate the source code and how it actually constructs the source code. performs tasks such as storage reservation and control functions `
macros
sets of instructions that are repeatedly used in a program. they’re written independently and embedded when required, and called using an identifier name
comments
not interpreted by the program, but help with understanding
system calls
a message sent to the kernel of the OS to allow interaction e.g. access hardware or new processes
bitwise operations
fast and simple operations performed by the CPU that treat each bit individually
mask
a number used alongside AND, OR and XOR to identify, remove or set a single bit/group of bits in an address/register
