Computer Architectures and Assembly Language Programming Flashcards
A basic computer system consists of?
CPU System Clock Primary Memory (RAM) Secondary Memory (HHD, SSD) Peripheral I/O Devices Bus
The CPU does what?
Executes instructions
Controls the transfer of data across the bus
The CPU consists of?
Control Unit (CU)
Arithmetic Logic Unit (ALU)
Registers
The Control Unit does what?
The CU directs the execution of instructions
The Arithmetic Logic Unit does what?
The ALU performs arithmetic and logical operations on data stored in registers
Registers are?
Registers are binary storage units within the CPU
The System Clock does what?
Generates a clock signal to synchronize the CPU and other clocked devices
Primary Memory is?
Often called Random Access Memory (RAM)
Can be written to and read from
Is volatile
Is used to store program instructions and program data (variables)
Consists of a sequence of addressable memory locations
The Bus is?
A set of parallel data/signal lines
Is used to transfer information between computer components
Often subdivided into address, data, and control busses
Secondary Memory is?
Is used to hold a computer’s file system
Is non-volatile read/write memory
Usually embodied on a hard disk drive (HDD)
Peripheral I/O Devices do what?
Allow communication between the computer and the external environment
Accumulator Machines are a type of CPU Architecture where?
Operands for an instruction come from the accumulator register (ACC) and from a single location in RAM
ALU results are always put into the ACC
The ACC can be loaded from or stored to RAM
Load/Store Machines are a type of CPU Architecture where?
Only load and store instructions can access RAM
Other instructions operate on specified registers in the
register file, not on RAM
Registers are more quickly accessed than RAM, so this is fast
RISC type Architecture:
Uses only simple instructions that can be executed in one machine cycle
Machine instructions are always the same size
CISC type Architecture:
May have instructions that take many cycles to
execute
Machines instructions vary in length, and may be followed by “immediate” data
The Instruction Cycle is?
Also called the fetch-execute or fetch-decode-
execute cycle
The CPU executes each instruction in a series of
small steps:
1) Fetch the next instruction from memory into the
instruction register (IR)
•The Program Counter register (PC) contains its address
2) Increment PC to point to the next instruction
3) Decode the instruction
4) If the instruction uses an operand in RAM, calculate its address
5) Fetch the operand
6) Execute the instruction
7) If the instruction produces a result that is stored in RAM, calculate its address
8) Store the result
Assembly Language Programs consist of?
A series of statements, each corresponding to a machine instruction
Each statement in an Assembly Language Programs consists of?
An opcode, and a variable number of operands
Instructions are stored?
Sequentially in memory
What can optionally prefix any statement?
A label
Pseudo-op give?
The assembler extra information but do not generate machine instructions
Assemblers do what?
They translate assembly source code into machine code
Von Neumann architecture RAM contains?
Both data and programs (instructions)
In Harvard architecture data and programs are?
stored in separate memories