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- How Hardware and Software Work Together
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- How hardware and software interact
- How system resources help hardware and software communicate
- How BIOS and device drivers are used to send instructions to hardware
- How different operating systems work
- The steps involved in booting your computer
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- Software
- Intelligence of the computer
- Determines what hardware is present
- Decides how hardware is configured and used
- Uses hardware to perform tasks
- Consists of programs that instruct computers to perform specific tasks
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- Software that controls a computer
- Manages hardware
- Runs applications
- Provides user interface
- Stores, retrieves, and manipulates files
- Communicates with hardware using system resources
- Does not relate directly with hardware; uses BIOS or device drivers for
the interface
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- BIOS (basic input/output system) and device drivers
- Operating system (OS)
- Application software
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- System BIOS
- Startup BIOS
- To control startup of computer
- CMOS setup
- To change setup information
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- Small programs stored on hard drive that tell computer how to
communicate with an I/O device
- Necessary for communication between OS and more complex devices
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- Works with system BIOS and device drivers to provide instructions to
hardware to perform tasks
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- Tools used by hardware or software to communicate with the other:
- Memory addresses
- I/O addresses
- Interrupt request numbers (IRQs)
- Direct memory access (DMA) channels
- All four types depend on certain lines on a bus on the motherboard
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- 8-bit ISA bus had a limited number of system resources available to it
- Number was increased with invention of 16-bit ISA bus
- Each line on a bus can perform several functions (multiplexing)
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- Line on a bus that a device uses to alert the CPU that it needs
servicing
- Interruptions to CPU are called hardware interrupts
- Polling is an alternative to an interrupt
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- Preconfigured assignments make it easier to configure devices and avoid
conflicts with other devices
- COM1 and COM2 (for serial devices such as modems)
- LPT1 and LPT2 (for parallel devices such as printers)
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- Hexadecimal numbers, often written in segment/offset form, assigned to
RAM and ROM so that the CPU can access both
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- CPU has fixed number of memory addresses, determined by CPU and the bus it is
using
- They can be assigned to any type of physical memory in the system that
needs to be addressed by the CPU
- Once addresses have been assigned (usually during boot process), CPU
sees physical memory as a single list that can be accessed using memory
addresses
- Number of memory addresses partly depends on size of memory bus
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- Process of copying programs from ROM to RAM for execution
- If ROM programs are executed directly from ROM chips, memory addresses
are assigned to this ROM
- If programs are first copied to RAM, and then executed, the same memory
addresses are assigned to this area of RAM
- Also called shadow RAM
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- Numbers the CPU can use to access hardware devices, in much the same way
it uses memory addresses to access physical memory
- Also called port addresses or ports
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- Provide shortcut method so an I/O device can send data directly to
memory, bypassing the CPU
- A chip on the motherboard contains DMA logic and manages the process
- Each channel requires two lines to manage it:
- One for DMA controller to request clearance from CPU
- One used by CPU to acknowledge that DMA controller is free to send data
over data lines without interference from CPU
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- Refers to the computer bringing itself up to an operable state without
user intervention
- Hard boot (cold boot)
- Involves initially turning on power with on/off switch
- More stressful than soft boot because of initial power surge through
equipment
- Soft boot (warm boot)
- Uses OS to reboot
- Faster than hard boot
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- Simplifies installation of hardware devices
- Rather than having to reset DIP switches and jumpers, OS and/or startup
BIOS automatically configures hardware devices to reduce or eliminate
conflicting requests for system resources
- Applies to OS, BIOS on the motherboard, and BIOS on devices
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- Startup BIOS tests essential hardware components (power-on self test or
POST)
- Setup information is used to configure both hardware and software
- Hardware components are assigned system resources they will later use
for communication
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- Startup BIOS finds the OS, which is loaded, configured, and executed
- Hardware devices are matched up with the BIOS and device drivers that
control them
- Some application software may be loaded and executed
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- Startup BIOS is in control for first three steps and beginning of the
fourth, where control is turned over to the OS
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- Step 1: POST
- Step 2: ROM BIOS startup program searches for and loads an OS (most
often from logical drive C on the hard drive)
- Step 3: OS configures the system and completes its own loading
- Step 4: User executes application software
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- Stands for automatically executed batch program
- Lists OS commands that are executed automatically each time OS is loaded
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- Path command (eg, PATH C:\;C:\PCTOOLS;)
- Directs OS to look in two different directories for program files
- Restart command (Restart.com)
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- Set command
- Appends a path to Path command without editing existing Path command
line itself
(eg, SET PATH=%PATH%;C:\VERT)
- Creates and assigns a value to an environmental variable that can later
be read by an application (eg, SET MYPATH=C:\VERT)
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- How hardware and software work together
- What happens when a PC is turned on OS is loaded
- System resources
- Interrupt request number (IRQ)
- Memory addresses
- I/O addresses
- DMA channels
- Booting up the computer
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