CSC 105 : Foundations of
Computing
Dr. Thomas A. Q. Tawiah
Lecture 4
3/31/2023
The components of the system unit
• The system unit is the case (housing unit) that
contains the CPU and main memory of the
computer.
• It is made up of metal and plastics to protect
the components.
Input peripherals
System unit
Figure 1 Computer System
Output peripherals
System unit
Motherboard
• Some components
– Processor (CPUs, GPUs)
– hard disk drives (solid state drives)
– Bus
– Memory (RAM, ROM, Flash Memory, CMOS)
– Expansion slots
– Port/connector
– System clock
– BIOS (Basic Input/Output System), a software
that stores the settings of the system on CMOS.
Some system unit components
• The processing function (instruction
interpretation and execution is carried out by
either the CPU (central processing unit ).
• The CPUs are typically integrated processor
cores (GPUs or microprocessors).
• Processors contain control unit and arithmetic
and logic unit.
• Processors (Intel, IBM, NVidia)
– The processor consist of ALU and control unit.
– It is responsible for fetching (data and
instructions), and execution of instructions
(program).
– The operations of a processor is split into four
steps, collectively, known as machine cycle.
• Machine cycle
– Fetch
– Decode
– Execute
– Store
• BIOS manages data flow between the
operating system and the attached devices
(disk drives, keyboard, mouse, video
adaptors, etc). It performs hardware
initialization during booting.
• Disk drive
– Hard disk drive (magnetic/ optical)
– Solid state drive ( all integrated circuit, no
moveable part)
• Other components
•
•
•
•
Expansion slots
Adapter cards (MIDI, modem, HD TV tuner)
Ports (attach to the motherboard)
Connectors (attach to the other device)
• Memory types
– ROM (read only memory)
– RAM (random access memory)
– Flash Memory
• Information representation
– Bits/byte/word (bit, 8-bit, 16/32 bit)
– ASCII and EBCDIC representations
Online assignment: Due on the 15th March 2023
• As a student in a drafting class, your instructor has challenged you to
design your dream home by using an application software wherever
possible. Form a team of three people that will determine how to
accomplish this objective. One team member should compare and
contrast two programs that can be used to create a two-dimensional floor
plan, another team member should compare and contrast two computeraided design programs that can create a more detailed design of the
house, and the third team member should compare and contrast two
programs that can assist with other aspects of the design process such as
landscaping and interior design.