Video Content Lesson 5 Flashcards
Organization
Computer Hardware Types CPU RAM ROM Erasable PROM Memory Addressing Cache Memory Virtual Memory
Computer Hardware Types
Most share the same core architecture
Mainframe (Large, does not communicate well with other computers)
Server (Server’s purpose to service requests) (receives requests, processes requests, returns data back to the requester)
Workstation (PC (anything) that requests information from the server)
Network appliances (a computer, but limited functionality–Router, Firewall, Switch)
PDAs (personal digital assistants) and smartphones (newest type of computer hardware)
CPU
Parts of Computer
Central Processing Unit (CPU)
Control Unit (accesses and interprets instructions)
Arithmetic Logic Unit (ALU) - performs arithmetic and logic functions
Registers - fast memory within the CPU
Clock - circuit that emits pulses at a standard frequency
RAM
Randum Access Memory (RAM) (real memory)
Real memory - slower, more abundant memory
Dynamic Ram - cheaper (uses capacitors, with lose their charge)
Must be peiodically refreshed (slower, cheap)
Static Ram - flip-flop circuit and doesn’t lose charge if powered up
Faster but more expensive
ROM
Read-only memory (ROM) (real memory)
Lowest-level instructions that never change (POST)
Power On Self Testing (POST)
Programmable read-only memory (PROM) (Write once, then ROM) (Ex-Modem)
Erasable PROM
Erasable programmable read-only memory (EPROM)
BIOS loaded here
UV window used to erase memory
Electrically Erasable programmable read-only memory (EEPROM)
EX - compactFlash Card
Memory Addressing
1-Register - address of a CPU register
2-Implied - operation performed using a CPU register
3-Direct-actual memory location
4-Indirect - address of memory location that contains the actual data’s address
Cache Memory
2 types of usage of memory
Cache - small, high-speek memory on the CPU
Does NOT require multiple clock cycles, as in real memory
Virtual Memory
Virtual Memory - allows programs to address memory larger than physical memory
Memory Management Unit (MMU) translates addresses
processes requests for memory access
MMU translates address into a PAGE FRAME address
Machine Operation
Hardware-Software Machine Types Execution Cycle Scalar Processors CPU Types Capabilities
Hardware-Software
Hardware (any part you can touch) Software is any set of instructions Machine Instructions/Source Code Executable Code Source Code Opt/Precompiled Code (Intermediate Code) Firmware (Kind of hardware AND kind of software)
Machine Types
Real Machine (see and touch - hardware designed to accept instructions and produce a result when instructions are executed) Virtual Machine - doesn't really exist (software that emulates the functionality of a real machine) JAVA - Compile to machine executables OR compile it to bytecode (BUT must be running virtual machine for its particular type of real machine) Allows developers to write one set of software that can run on many different platforms
Execution Cycle
1-Fetch (instruction from memory)
2-Decode (instruction)
3-Execute (instruction)
Linear function, one action at a time (cycle must complete before starting on the next instruction)
PIPELINING ( allows multiple actions at a single time, as soon as an instruction is completed begins executing the next actions)
Scalar Processors
1-Scalar Processor (linear execution, single instruction at a time, can be pipelined)
2-Superscalar processor (multiple instructions at the same time, each pipeline stage can occur simultaneously, fetch 2 or more at same time)
CPU Types
1-Complex Instruction Set Computing (CISC)
Each instruction preforms multiple steps
Compilers are generally simplern
Performance may suffer
2-Reduced Instructions Set Computing (RISC)
Fewer instructions (small and fewer)
Often requires multiple steps to accomplish task
Compilers can be more complex
Capabilities
Multitasking (execute 2 or more processes at the same time on a single CPU by switching among processes, giving each one a finite time slice, put into back of line, repeat)
Multiprocessing (executing 2 or processes on multiple CPUs at the same time, allows multiple processes running on seperate CPUs)
Multithreading (Subdividing a process into 2 or more subprocesses, or threads, and executing them at the same time on one or more CPUs (spell check and grammar check)
OR allow multiple users to access the same shared process, each with its own local data space
Most modern machines support all 3 (Multitasking, Multiprocessing, and Multithreading)
Operating Modes/Protection Mechanisms
Operating States Operating Modes Storage Types Layering Abstraction Least Privilege Accountability Definitions
Operating States
1-Single State (Capable of handling Information at only one security level at a time)
2-Multistate (Certified to handle Information at multiple security levels at the same time)
Very Exensive and difficult to maintain
Requires specific protection mechanisms to prevent data from crossing security level boundaries
Operating Modes
1-User Mode (basic operating mode when executing user programs)
Only a subset of the full instruction set is available (protection from faulty or malicious code)
2-Privileged Mode (Full instruction set is available–therefore NO protection from faulty or malicious code
ALSO KNOWN AS Supervisor Mode or Kernel Mode
Storage Types
Primary Storage (registers on CPU) Real Storage (RAM--Memory for Programs (NO direct CPU access) Secondary Storage (Nonvolatile storage (disks and tapes)) Virtual Storage (Memory space that can exceed real memory--Uses Frames)
