shows how hardware and software works together, and define the parts involved in the interaction between HW and SW

1. How Hardware and Software Work Together
Zainab Almugbel
Community College
Imam AbdulRahman Bin Faisal University

2. You Will Learn…
• How hardware and software interact
• How system resources help hardware and
software communicate
• The steps involved in booting your
computer

4. Categories of PC Software
• BIOS (basic input/output system) and
device drivers
• Operating system (OS)
• Application software

5. Categories of BIOS (Firmware)
• System BIOS
– To control I/O devices
• Startup BIOS
– To control startup of computer
• CMOS setup
– To change setup information

6. Device Drivers
• 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

7. Operating System (OS)
• Works with system BIOS and device
drivers to provide instructions to hardware
to perform tasks

8. System Resources
• 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

9. System Resources

10. ISA Slot
Stands for "Industry Standard Architecture." ISA is a type of
bus used in PCs for adding expansion cards. For example,
an ISA slot may be used to add a video card, a network
card, or an extra serial port

12. IRQs

13. Use Device Manager to See
How IRQs Are Assigned

14. Use Device Manager to See
How IRQs Are Assigned

15. Memory Addresses
• Hexadecimal numbers, often written in
segment/offset form, assigned to RAM
and ROM so that the CPU can access
both

16. How Memory Addresses
Are Assigned
• 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

17. I/O Addresses
• 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

18. I/O Addresses

19. DMA Channels
• 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

20. Booting up Your Computer
• 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

21. Functions Performed
During the Boot
1. Startup BIOS tests essential hardware
components (power-on self test or
POST)
2. Setup information is used to configure
both hardware and software
3. Hardware components are assigned
system resources they will later use for
communication
continued…

22. Functions Performed
During the Boot
4. Startup BIOS finds the OS, which is
loaded, configured, and executed
5. Hardware devices are matched up with
the BIOS and device drivers that control
them
6. Some application software may be
loaded and executed

23. Summary
• 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