This document provides an overview of computer organization topics including motherboard types (Full AT, Baby AT, ATX), computer components (communication ports, SIMMs/DIMMs, processor sockets, cache memory), bus architectures (ISA, PCI, AGP, USB, VL-Bus), and memory module types (EDO, RAM, DRAM, SRAM, SDRAM, VRAM, WRAM, RIMM). It compares features of motherboard types, serial/parallel ports, SIMMs/DIMMs, processor socket types (LGA, PGA, BGA, ZIF), and describes the roles of components like cache memory and bus structures.

1. COMPUTER ORGANIZATIONS
PRESENTATION (MIT81)
By Timothy Tanhueco

2. IN THIS PRESENTATION, WE WILL
FOCUS ON:
• Motherboard types
• Computer components
• Bus architectures
• Basic compatibility guidelines for IDE(Integrated Drive
Electronics) and SCSI(Small Computer Systems Interface)
• Non-Parity Chips:
EDO,RAM,DRAM,SRAM,SDRAM,VRAM,WRAM,RIMM
• Locations and physical characteristics: Memory Bank,
Memory Chips, Parity Chips, SIMMS(Single In-Line
Memory Modules)

3. MOTHERBOARD
OTHER NAMES:
• “Backbone of the operations”
as the system(CPU,GPU or hard
drive) cannot run without it
• “Logic Board”
• “Baseboard”
• “System Board”
• “Mainboard”
• “Main Circuit Board”
• “Planar Board”
• “mobo” for short(motherboard)
• Is present on every computer,
laptop, tablet and smartphone
and their components and
functionalities are the same
• Difference: Component size
differs and the way they are
accompanied on the
motherboard varies due to
space availability
• Different motherboards vary
on capabilities, features,
limitations and physical
size/shape

4. MOTHERBOARD TYPES
Full AT Motherboard
Baby AT Motherboard
ATX Motherboard

5. FULL AT MOTHERBOARD
• Have bigger physical dimensions
with hundreds of millimeters;
Cannot fit on mini desktops
• Bigger size = you can install new
drivers
• Has sockets and 6-pin plugs as
power connectors, but not easily
identifiable
• The early motherboard models
only had a keyboard connector

6. BABY AT MOTHERBOARD
• Introduced in 1987
• A smaller version of the Full AT
motherboard, used in the IBM
PC/AT; Only measured at 8.5”
• Was the 1st motherboard to have
built-in sockets for I/O ports (be it
serial or parallel)
• Was superseded by the ATX
motherboard

7. ATX MOTHERBOARD
• Also known as “Advanced
Technology Extended” motherboard
• Developed by Intel in 1995:
Introduced I/O ports + connectors
directly on the motherboard
• An improved version of the AT
motherboard
• Smaller size compared to the AT
motherboard = connected
components can be interchanged
whereas you cannot interchange
components on an AT
motherboard

8. AT MOTHERBOARD ATX MOTHERBOARD
Is bigger compared to an ATX motherboard Is smaller compared to an AT motherboard
Has limited connector interchangeability Can be interchanged easily

9. BONUS CONTENT:
SO, THERE’S A “MOTHERBOARD” BUT THERE’S
ALSO A…DAUGHTERBOARD?!
• A circuit board attached/plugged
to the motherboard or any similar
expansion card to extend its
features and services
• Complements the existing
functionality of a motherboard or
expansion card
• Other names: “Daughter Card”,
“Riser Card”, “Piggyback
Board” or “Mezzanine Board”

10. It does NOT exist in the computer world
BONUS CONTENT:
HOW ABOUT A “FATHERBOARD” OR “SONBOARD”?
HOW COME? THINK ABOUT THIS:
Every computer socket or hole is “FEMALE”
Every computer plug or pin is ”MALE”

11. COMPUTER COMPONENTS
Communication Ports
SIMM & DIMM
Processor Sockets
External Cache Memory

12. COMMUNICATION PORTS
2 MAIN PORTS:
SERIAL PORTS
PARALLEL PORTS
A communication port allows filters
to communicate with an external
digital system

13. SERIAL PORTS
• Also called “Asynchronous Port”
• An interface where peripherals are
connected as a communication channel
using a ”serial” (bit stream) protocol
• Usually identified on IBM-compatible
computers as “COM” (communication)
ports
• This port can be found at the back of the
computer and is part of the motherboard
• D-shaped, a male connector and has 9
pins (small connector); Most common
is 25 pins
• Because of the USB and the FireWire,
serial ports are now rarely used
• The newest computers and laptops no
longer have serial ports
• The “male port”
< D89 SERIAL PORT
• The following hardware
components are
compatible with serial
ports:
- MOUSE
- MODEM
- NETWORK
- PRINTER
*OLD GAME
CONTROLLER

14. PARALLEL PORTS
• Created by “Centronics” Company which
named the said ports: “Centronics
Connector”, “Centronics Interface” or
“Centronics Port”
• An interface where the peripherals of the
computer are communicated in a
“parallel” manner > Data is transferred
in and out in more than 1 wire
• Carries 1 bit on each wire = multiplies
the transfer rate over a single wire
• Was later developed by Epson
• D-shaped, a female connector and has
25 holes
• Because of the USB and the FireWire,
parallel ports are now rarely used
• The newest computers and laptops no
longer have parallel ports
• The “female port”
• The following hardware
components are
compatible with parallel
ports:
- PRINTER
- SCANNER
- HARD DRIVE
*OLD GAME
CONTROLLER

15. SERIAL PORT VS PARALLEL PORT, A DIRECT COMPARISON
KEY POINTS SERIAL PORT PARALLEL PORT
PURPOSE Used for serial data transmission Used for parallel data transmission
TRANSMISSION SPEED Slow compared to parallel port Fast compared to serial port
REDUNDANCY “Bottom-up model” is better to
ensure minimal redundancy and
focuses on reusability
“Top-down model” has high
redundancy ratio as the size
of projects increases
NO. OF WIRES CONNECTED Less compared to a parallel port More compared to a serial port
CAPABILITY Able to transmit a single stream of data Able to transmit multiple data streams
DATA-SENDING MECHANISM Sends data bit by bit at a time Sends multiple bits at the same time in a
parallel fashion
PORT TYPE Uses “male” ports (plugs) Uses “female” ports (sockets)
APPLICATIONS/HARDWARE
USED
Modems, Security Cameras,
Device Controllers, Mouse,
Networks, Printers
Printers, Scanners, Hard
Drives, CD Drives, Device
Controllers,

16. SINGLE IN-LINE MEMORY MODULES
(SIMM)
• Little circuit boards having
notches where RAM chips
are fixed
• Made of metal (usually gold
or tin)
• 2 types: 30 pins and 72 pins
• Has a maximum I/O of 32 bits
per channel for data transfers

17. DUAL IN-LINE MEMORY MODULES
(DIMM)
• Also, little circuit boards
having notches where RAM
chips are fixed
• Also made of metal (usually
gold or tin)
• 3 types: 168 pins, 184 pins
and 240 pins
• Has a maximum I/O of 64 bits
per channel for data
transfers

18. S I M M V S D I M M :
A DIRECT
COMPARISON
S.NO SIMM DIMM
1.
In SIMM, Pins present in either facet
are connected.
DIMM pins are freelance.
2.
SIMM supports 32 bit channel for data
transferring.
DIMM supports 64 bit channel for data
transferring.
3. SIMM consumes 5 volts of power. DIMM consumes 3.3 volts of power.
4.
SIMM provides the storage 4 MB to 64
MB.
DIMM provides the storage 32 MB to 1
GB.
5.
The classic or most common pin
configuration of the SIMM module is 72
pins.
The foremost common pin configuration
of the DIMM module is 168 pins.
6. SIMMs are the older technology.
DIMMs are the replacement of the
SIMMs.
7. SIMMs are installed in pairs at a time. DIMMs are installed one at a time.
8.
SIMMs are used by 486 CPU as well as
early Pentium computers.
DIMMs are used by modern Pentium
computers.
9.
The length and width of SIMM are
respectively 4.25 inches and 1 inch.
The length and width of DIMM are
respectively 1.67 to 5.25 inches and 1 to
1.75 inches.
10. There are single notches in SIMMs. There are two notches in DIMMs.

19. PROCESSOR SOCKETS
4 MAIN TYPES:
LAND GRID ARRAY (LGA)
PIN GRID ARRAY (PGA)
BALL GRID ARRAY (BGA)
ZERO INSERTION FORCE (ZIF)
- Sockets are placed on the
motherboard plate of a computer
where a processor is inserted
- Acts as a connector to connect
and provide electrical and
mechanical connections between
the CPU and the motherboard

20. LAND GRID ARRAY (LGA)
• A socket for integrated
circuits
• Needles are in the CPU
socket with metallic points in
the lower area of the
processor
• Can be electronically
connected to the
motherboard by soldering

21. PIN GRID ARRAY (PGA)
• An integrated circuit shaped like a
square or rectangle whose pins
are aligned in a regular matrix
• Pin may not cover the entire
board with a standard spacing of
2.54mm
• A “PGA grip” applies a
compressive force once the
handle is in place to allow better
mechanical retention and avoid
the risk of bending the pins when
inserting the processor into the
socket

22. LGA VS PGA
LGA PGA
Socket with pins you install on the
processor chip by soldering
Places pins on the processor chip, then
embedded to a socket with fittingly spaced
holes

23. BALL GRID ARRAY (BGA)
• Not technically considered a
“socket” as the microprocessors
are already permanently mounted
on this socket
• Not as famous as the other
sockets
• Copper balls are soldered directly
to the motherboard instead of
metallic pins
• Can be found in laptops, mobiles,
memory chips and any other small
electronic boards

24. ZERO INSERTION FORCE (ZIF)
• An evolution of PGA
• Pins are now carried by the
microprocessor and is
inserted into the socket
connectors
• A mechanism defined by
NOT exerting any force
while installing or removing
a processor from a socket

25. CACHE MEMORY
• A memory which looks like a
processor chip within a device
• A high-speed, volatile memory to
speed up and synchronize with
the processor and memory to act
as temporary storage
• Used for maintaining the speed
between the CPU and main
memory
• Fast process speed = Slow main
memory, thus cache memory is
used

26. EXTERNAL CACHE MEMORY
• Also called as “Level 2 Cache”
• An area between the CPU
and a system bus where
high-speed memory is
located to store CU
input/requested instructions

27. BUS STRUCTURES
TYPES:
Industry Standard Architecture Bus (ISA)
Peripheral Component Interconnect Bus (PCI)
Accelerated Graphics Port Bus (AGP)
Universal Serial Bus (USB)
VESA Local Bus (VL-Bus)
- A “shared transmission medium”:
multiple components or devices
share the same bus structure to
transmit information signals to each
other
- Only 1 pair of devices can use a
certain bus to communicate with
each other successfully
- If multiple devices transmit
information signals through a single
bus at the same time, it gets
overlapped and jumbled

28. BUS STRUCTURES (CONT.)
• Has 50-100s of distinct lines
where each line is meant for
certain functions
• 3 functional groups:
Data lines- coordinates in transferring data among
system components; Have 32, 64, 128 or more lines
and it defines the width of the data line; Transfers
only 1 bit at a time
Address lines- Determines the source or
destination of data presented by the data line, the
number of address lines together is determined by
its width which also determines the memory capacity
of the system
Control lines- Controls the usage and access of the
data buses and address buses, consists of
command and timing information

29. CONTROL LINE FUNCTIONS
• Memory Write: This command causes the data on the data bus to be placed over the addressed
memory location.
• Memory Read: This command causes the data on the addressed memory location to be placed on
the data bus.
• I/O Write: The command over this control line causes the data on the data bus to be placed over
the addressed I/O port.
• I/O Read: The command over this control line causes the data from the addressed I/O port to be
placed over the data bus.
• Transfer ACK: This control line indicates the data has been received from the data bus or is
placed over the data bus.
• Bus Request: This control line indicates that the component has requested control over the bus.
• Bus Grant: This control line indicates that the bus has been granted to the requesting component.
• Interrupt Request: This control line indicates that interrupts are pending.
• Interrupt ACK: This control line provides acknowledgment when the pending interrupt is serviced.
• Clock: This control line is used to synchronize the operations.
• Reset: The bit information issued over this control line initializes all the modules.

30. INDUSTRY STANDARD ARCHITECTURE BUS
(ISA)
“EXTENDED” Industry
Standard Architecture Bus
(ISA)
• An “extension” of ISA
from 16 to 32 bits
• Introduced in 1998 by the
“Gang of Nine”, a group
of PC manufacturers
• Introduced by IBM in 1981
• A computer bus that allows
additional expansion
cards/boards to be
connected to a computer’s
motherboard
• Ever since the creation of
PCI buses in 1990, usage of
ISA buses disappeared
• Have 8 and 16 bits

31. PERIPHERAL COMPONENT INTERCONNECT BUS
(PCI)
• Connects the CPU and expansion
boards (modem cards, network
cards, sound cards) together
• Normally plugged into expansion
slots of the motherboard
• General standard for a PC
expansion bus
• Replaced ISA and VL-Bus, but
was soon replaced by USB
• Have 32 and 64 bits

32. ACCELERATED GRAPHICS PORT BUS (AGP)
• Used for high-speed video
output
• Used to connect graphic
cards to computer’s
motherboard to accelerate
3D output for an HD video
• Used for 3D graphics, HD
games and architectural
graphics
• Provides faster connectivity
and output compared to PCI
• Has 32 bits

33. UNIVERSAL SERIAL BUS (USB)
• Enables communication between
devices and a host controller (PC
or smartphone)
• Connects peripherals like
digicams, mice, keyboards,
printers, scanners, media
devices, external hard drives and
flash drives
• Enhances “plug-and-play”
• Allows “hot swapping”

34. V I D E O E L E C T R O N I C S S TAN D A R D S AS S O C I AT I O N L O C AL B U S
(VL-BUS)
• Shortened for “VESA Local
Bus”- A bus created by
VESA
• Used in computers with over
486 CPUS!
• Provides high-speed data
transfer between the CPU
and peripherals
• 32-bit channels with 3 slots
on the motherboard

35. BUS EXPANSION CARDS

36. BASIC COMPATIBILITY GUIDELINES FOR:
• Integrated Development Environment (IDE):
Advanced Technology Attachment (ATA)
Advanced Technology Attachment Packet Interface (ATAPI)
Ultra Direct Memory Access (ULTRA-DMA)
Enhanced Integrated Development Environment (EIDE)
• Small Computer Systems Interface (SCSI):
Wide
Fast
Ultra
Low Voltage Differential (LVD)

37. INTEGRATED DEVELOPMENT ENVIRONMENT (IDE)
• More commonly known as ATA ,
ATA-1 or PATA (Parallel ATA)
• First developed by Western
Digital and Compaq in 1986 for
compatible hard drives, CD and
DVD drives
• Differs from SCSI and ESDI
(Enhanced Small Disk Interface)

38. ADVANCED TECHNOLOGY ATTACHMENT
(ATA)
• Generally known as “IDE” and is
referred to as “ATAPI” or “ATA-1”
• A standard physical interface for
connecting devices within a computer
• Allows hard disks and CD-ROMS to
be internally connected to the
motherboard and perform basic I/O
functions

39. ADVANCED TECHNOLOGY ATTACHMENT PACKET
INTERFACE
(ATAPI)
• Allows greater variety of
devices to be connected to a
computer than ATA (be it
IDE/PATA and SATA) on its
own
• Allows IDE (ATA) and SATA
controllers to support optical
drives

40. ULTRA DIRECT MEMORY ACCESS
(ULTRA-DMA)
• Shortened to “UDMA” or “Ultra ATA”
• Developed by Quantum and Intel
• Transfers data between a computer’s
hard disk and memory
• UDMA hard drive maximum burst rate
= 33mbps
• With this technology, programs can
open and execute faster
• Cyclical Redundancy Checking
(CRC): A built-in utility program
installed at a UDMA that helps
protect data integrity

41. ENHANCED INTEGRATED DEVELOPMENT
ENVIRONMENT
(EIDE)
• Also called “Fast ATA” or “ATA-2”
(vs ATA or ATA-1)
• Created by Western Digital in
1994
• A hard drive interface which
succeeded IDEs in terms of faster
I/Os
• Refers to a set of extensions for
the ATA-1 standard
• Acts as intermediary between a
computer and a mass storage
device (Similar to UDMA)

42. PARALLEL ADVANCED
TECHNOLOGY ATTACHMENT
(PATA)
- Also known as “Parallel ATA” or “P-
ATA”
- Used during the 1980s
- A standard for connecting hard drive
to computer systems
- Is based on “parallel signaling
technology” vs SATA’s “serial
signaling technology”
- Transfers 16 bits at a time
- Cables have 40 pins attached to a 40
or 80-conductor ribbon cable
SERIAL ADVANCED
TECHNOLOGY ATTACHMENT
(SATA)
- Also known as “Serial ATA” or “S-
ATA”
- A bus interface used to connect host
bus adapters with mass storage
devices like hard drives
- Commonly used to connect hard
drives to a host system like a
motherboard
- Is an upgraded version of PATA
- Transfers 1 bit at a time
- Cables have 7 pins attached to a 15-
pin power cable

43. IDE COMPATIBILITY GUIDELINE RESOURCE:
• https://kb.iu.edu/d/adlt

44. SMALL COMPUTER SYSTEMS INTERFACE
(SCSI)
• The acronym can be pronounced
as “Skuh-zee” > “Scuzzy”
• A standard set by the American
National Standards Institute
(ANSI) that allows PCs to
communicate with peripheral
hardware (hard drives, tape
drives, CD-ROMs, printers,
scanners) faster
• More flexible than PATA

45. SCSI
CONNECTOR
STANDARDS

46. LOW VOLTAGE DIFFERENTIAL SIGNALING
(LVDS)
• A high-speed, long distance digital
interface for serial communication (1
bit at a time) over 2 copper wires
(differential) placed 180 degrees
from each other
• Uses 2 wires for each electrical path
for high noise and crosstalk immunity
where each wire is positive (+) and
negative (-) > The receiver at the end
derives the signal between the 2
• Reduces noise emissions by making
noise more findable and filterable as
it protects its performance
• Is the solution for low power
consumption, high noise immunity for
high data rate transfers

47. SCSI COMPATIBILITY GUIDELINE RESOURCE:
• https://kb.iu.edu/d/aiqw
• https://www.datapro.net/techinfo/scsi_doc.html

48. NON-PARITY CHIPS
OR
NON-PARITY RAM
• As previously introduced, a
Random Access Memory (RAM) is
the working storage of the
computer system and is volatile
(stored data can be moved or
removed); Is the internal memory
• Non-Parity RAM do not have a 9th
bit used for parity checking and
doesn’t use the Error-Correcting
Code (ECC)
TYPES:
• External Data Random Access
Memory (RAM)
• Extended Data Out RAM (EDO)
• Dynamic RAM (DRAM)
• Static RAM (SRAM)
• Synchronous Dynamic RAM
(SDRAM)
• Video RAM (VRAM)
• Window RAM (WRAM)
• Rambus Inline Memory Module
(RIMM)
• Flash Memory

49. EXTERNAL DATA RANDOM ACCESS MEMORY
(RAM)
• Is “Read/Write” = Readable and Writable
• Since this is indirectly accessed through a
data pointer register, it has a slower access to
internal data memory
• Several 8051 devices provide on-chip XRAM
space that is accessed with the same
instructions as the traditional external data
space. This XRAM space is typically enabled
via dedicated chip configuration SFR registers
and overlaps the external memory space.
• Up to 64K bytes of external data memory are
stored
• Your hardware design may map peripheral
devices into the memory space where the
program needs to access external data
memory to program and control the peripheral,
referred to as “Memory-Mapped I/O”

50. EXTENDED DATA OUT RAM
(EDO)
• Also called “EDO DRAM”
• Introduced in 1994 to replace FPM
DRAM by Intel when they first
introduced the 430FX chipset that
supports EDO DRAM
• Is an early type of Dynamic Random
Access Memory (DRAM) chip
• Designed to improve the performance
of Fast Page Mode DRAM (FPM
DRAM) which was used in the 1990s
• It eliminates wait times by allowing a
new cycle to start while retaining data
output buffer from a previous cycle
active

51. DYNAMIC RANDOM ACCESS MEMORY
(DRAM)
• A type of RAM used in computing devices
(PC)
• Stores each bit in a separate passive
electronic component that is inside an
integrated circuit board > Each electrical
component have 2 values in 1 bit: 0 & 1
• A captivator needs to be refreshed more
often or the data fades
• Has 1 capacitor and 1 transistor per bit
vs Static RAM (SRAM) which requires 6
transistors
• The capacitors and transistors used are
very small
• A single memory chip can fit millions of
capacitors and transistors

52. SYNCHRONOUS DYNAMIC RANDOM
ACCESS MEMORY
(SRAM)
• A DRAM that is synchronous with the
system bus carrying data between
the CPU and the memory controller
hub
• Has a rapid response synchronous
interface which is perfectly in sync
with the system bus
• Waits for the clock signal before it
responds
• Has 64-bit modules with long 168-pin
DIMMs
• Access time = 6-12ns (nanoseconds)
• Is the replacement for DRAM and
EDO

53. STATIC RANDOM ACCESS MEMORY
(SRAM)
• A type of RAM that holds data in a “static
form” if the memory has power
• SRAM doesn’t need to be refreshed vs
DRAM where it needs to be refreshed more
often or the data fades
• Stores bits of data on 4 transistors using 2
cross-coupled inverters
• Like DRAM, it also uses 2 bits: 0 & 1
• During the read/write operation, 2 additional
transistors are used to manage the
availability to a memory cell
• To store 1 bit of memory, it needs 6 metal-
oxide-semiconductorfield-effect transistors
(MOFSET) which is a popular SRAM
• The other SRAM chip is the bipolar junction
transistor which is very fast, but consumes
a lot of energy

54. VIDEO RANDOM ACCESS MEMORY
(VRAM)
• Also known as “Frame Buffer” or
“Video Memory”
• A high-speed array of DRAM used to
store image and video data that a
computer displays
• An integrated circuit which serves as
a buffer between the CPU and the
video card
• Originally designed as a high-
resolution graphics adapter
• Higher video memory = Higher
capability of the system to handle
more complex graphics at a faster
rate

55. WINDOW RANDOM ACCESS MEMORY
(WRAM)
• Was developed by Samsung
Electronics (Not Windows)
• Optimized for graphic cards
• Faster than a VRAM
• It also uses a dual-ported structure
that simultaneously refreshes the
screen while text and images are
being drawn in the memory

56. RAMBUS INLINE MEMORY MODULE
(RIMM)
• Is a trademark of Rambus
Incorporated for the Rambus DRAM
(RDRAM) module
• A computer memory that resembles
DIMMs with 184 pins and is available
with built-in ECC support and Non-
ECC support at speeds up to 800
MHz
• Commonly used on Intel and Pentium
4 motherboards

57. BONUS RAM: FLASH MEMORY
• Started in 1984
• A type of non-volatile storage
medium that retains data after power
has been cut off
• Is like the form and operation of
solid-state drives
• Commonly used in flash drives,
printers, portable media players,
memory cards, small electronics

58. MEMORY BANK LOCATION AND
PHYSICAL CHARACTERISTICS
• The logical storage within a computer
memory used for storing and
retrieving frequently used data
• Part of a standard RAM or cache
memory used for easily accessing
and retrieving program and standard
data
• A memory chip is equally divided into
2 parts (banks)- Even bank and Odd
bank:
Even bank = gives LOWER bytes > LOWER BANK (LB)
Odd bank = gives HIGHER bytes > HIGHER BANK (HB)
• This allows access to 2 aligned
memory locations from both banks
simultaneously and process 16-bit
data transfers

59. MEMORY BANK LOCATION AND PHYSICAL
CHARACTERISTICS
(CONT)
• “A0” is a variable not used for byte
selection
• The Least Significant Bit of address
is reserved for bank selection
• A0=0 will select Even bank
• Bus High Enable (BHE) signal is
used for the selection of Odd bank
• The processor will combine these 2
signals to decide which data to
transfer

60. MEMORY BANK LOCATION AND PHYSICAL
CHARACTERISTICS
(CONT)
In this case, the first machine cycle
generates an odd address (A0=1)
transfer lower order 8 data bits on a
higher-order data bus. In the
second machine cycle, the higher-
order data bus will be transferred to
the lower-order data bus.
BHE A0 Transfer Types
0 0
16-0bit data transfer from
both HB and LB
0 1 8-bit data transfer from HB
1 0 8-bit data transfer from LB
1 1 None(Idle)

61. MEMORY CHIP
• An integrated circuit made of
millions of capacitors and
transistors that stores data or can
be used to process codes
• Can hold memory temporarily
through RAM or ROM
• It comes in different shapes and
sizes
• Can be connected directly while
some may need special drives
• An essential component of a
computer in which memory
storage plays a key role

62. PARITY CHIP
• A parity chip is used to check for
errors in RAM chips (vs Non-parity
which which has ECC)
• RAM parity checking: storing of
redundant parity bits representing the
parity (0 or 1) of a small amount of
computer data (1 byte) stored in RAM
and the subsequent comparison of
the stored and computed parity to
detect whether a data error has
occurred
• Parity errors is usually caused by
failing hardware or any external
elements disrupting computer
memory functions

63. PARITY CHIP (CONT)
• Fixing the errors usually involves
eliminating the external element or
failing hardware
• A memory parity error means 1 or
more of the stored data values carry
a different value when recalled than
it was stored > computers display a
“parity error” message, hangs up and
reboots
• It offsets the charge value which can
provide invalid commands for the
computer

64. SINGLE IN-LINE MEMORY MODULE
(SIMM)
LOCATION AND CHARACTERISTICS
• As previously discussed, SIMMs are
little circuit boards having notches
where RAM chips are fixed
• This was used to replace DRAM
chips which takes up most of the
space
• A SIMM chip is installed on a
separate circuit board and is plugged
into the motherboard at a
perpendicular angle
• Was replaced by DIMM in 1993 in
terms of the number of pins and price