1. COMP1321 Digital Infrastructure
Richard Henson
University of Worcester
December 2018

2. Week 11: Boot-up, standards, Network Operating System
Explain Windows boot up sequence
Explain role of network interface
Explain logging on locally and logging on to a network

3. Booting up: basics, local… or to a network?

4. 1. Check Power Supply… on/off switch pressed…
mains electricity reduced in voltage by power supply
IF electricity to the motherboard is the right voltage, etc.
Stage 2
back to sleep!

5. 2. Load/Run BIOS CPU starts loads BIOS (Basic Input Output System)
runs BIOS process
basic check if devices are actually present, electrically

6. POST program Part of BIOS checks hardware in a little more detail
uses CMOS settings to compare hardware configuration it finds with what was previously used and working
IF all good on to next stage…

7. Configuring Hardware
BIOS loads basic drivers for each hardware device detected
Devices should then be ready to work
drivers not loaded yet…

8. Motherboard System Bus
Controlled by BIOS
system bus software loaded
and run by CPU

9. Basic Video Only now does Video start… still basic settings
provides low resolution video output
enough to provide screen output!

10. BIOS completes… disk-based programs start
BIOS hands process to Bootstrap Loader
finds bootstrap program on hard disk
loads, runs boot programs…
control now passes to hard disk/memory…

11. Memory check & Loading Disk-based OS
POST checks RAM for loading programs, etc…
loads, runs essential processes of operating system
sets up full hardware drivers
sets up services…
sets up logon…

12. Providing a User Interface
CLI or GUI?
GUI by default
CLI window available…
Horses for courses!
Local or Networked
different configuration

13. Now in more detail…

14. Logon Once the operating system has been loaded…
user logon screen presented
Rapid local boot is fine…
but most organisational computers are on networks…
why?
why does network logon take so long?

15. “Policies”: Controlling User and System Settings
The Windows user’s desktop is controlled with policies
user policies
system policies
Configuring and using policies - essential part of any network administrator’s job!
could be 100s or 1000s of systems, & users

16. Storage of User/System Settings: Windows Registry
Early Windows extended DOS text files of system & user settings:
SYSTEM.INI enhanced CONFIG.SYS
WIN.INI enhanced AUTOEXEC.BAT
Windows 95 created a two dimensional structure… known as The Registry
principles later extended in Windows NT v4 to allow system and user settings to be downloaded to local registry across the network

17. Viewing/Editing the Registry
REGEDT32 from command prompt…
look but don’t touch!
contents should not be changed manually unless you really know what you are doing!!!
Registry data that is loaded into memory can also be overwritten by data:
from local profiles
downloaded across the network…

18. System Settings For configuration of hardware and software
different types of system need different settings
system settings for a given computer may need to be changed for particular users e.g. to change screen refresh rate for epileptics

19. User Settings More a matter of convenience for the user
mandatory profiles
users all get the same desktop settings!
anything added is lost during logoff!
roaming profiles - desktop settings preserved between user sessions
saved across the network…

20. What is The Registry? A hierarchical store of system and user settings
Five basic subtrees:
HKEY_LOCAL_MACHINE : local computer info. Does not change no matter which user is logged on
HKEY_USERS : default user settings
HKEY_CURRENT_USER : current user settings
HKEY_CLASSES_ROOT : software config data
HKEY_CURRENT_CONFIG : “active” hardware profile
Each subtree contains one or more subkeys…

21. The Windows Registry Six files (no extensions): Software
System – hardware settings
Sam, Security
not viewable through regedt32
Default – default user
Sysdiff – HKEY USERS subkeys
Also to be considered: ntuser.dat
user settings that override default user

22. Registry Files in Windows
HKEY_LOCAL_MACHINE \SYSTEM:
\system32\config\system
HKEY_LOCAL_MACHINE \SAM:
\system32\config\sam
HKEY_LOCAL_MACHINE \SECURITY
\system32\config\security
HKEY_LOCAL_MACHINE \SOFTWARE
\system32\config\software
HKEY_USERS \UserProfile
\winnt\profiles\username
HKEY_USERS.DEFAULT
\system32\config\default

23. Emergency Recovery if Registry lost or badly damaged
Backup registry files created during text-based part of windows installation
also stored in:
c:\windows\system32\config
have .sav suffix
only updated if “R” option is chosen during a windows recovery/reinstall
NEVER UPDATED backup is saved to
C:\windows\repair folder
no user and software settings
reboots back to “Windows is now setting up”

24. Backing up the Registry
Much forgotten… an oversight that may later be much regretted!!!
can copy to tape, USB stick CD/DVD, or disk
rarely more than 100 Mb
Two options;
Use third-party backup tool
e.g
Use windows “backup”
not recommended by experts!
but already there & does work!
to copy the registry if this tool is chosen, a “system state” backup option should be selected

25. Development of Communication Networks
Used for centuries before computers… (!)
Chronologically:
Telegraph (1840s)
Telephone (1910s)
Telex (1930s)
Internet & digital networks (1970s on)

26. Standards – why is it like this?
The basis of technological advancement (and human enterprise to support new technology…)
Some say standards stifle creativity (?!)
in fact, essential for developing stuff that fits together with other stuff…
especially important for communications….

27. Each network type developed its own standards for…
Creation of data
Format of transmitted data
Voltage
Error-checking
Receiving, storing, presentation of transmitted data

28. Standards for National and International Networks
Telegraph:
data transmitted within a particular country
National standards…
became International
International standards
initially along wires
then as radio waves

29. Telephone Initially National, like Telegraph network
International calling possible… required a standard
French-based standards became the Internationally recognised ones (CCITT)
Comité Consultatif International Téléphonique et Télégraphique

30. A Tale of Standards… (1) Roman Empire, 2000 years ago
streets in cities open sewers

31. A Tale of Standards… (2) Problem: how wide?
Romans needed crossing places
stone paths across the street
Chariots also used street
needed spaces in stones for chariot wheels
Problem: how wide?

32. What width would you choose?
Suggestions…
How did the Romans Decide?

33. Ways to agree a Standard
“De Facto”
A product or service that is a standard by virtue of its widespread use by interested users
“De Jure”
The standard devised by a committee of the organisation

34. Roman “Wheelbase” Standard “wheelbase” width agreed (4’ 8½’’)
used for chariots throughout Roman Empire
And much later for “horse and stagecoach”

35. New Technology, new standard?
Continued in UK as “standard gauge” when railway tracks started (1830s)
Was it still a good standard?

36. Breaking a standard?
The Great Western Railway tried to change the standard to 6’ 0’’
“Broad Gauge”… all their tracks
wider carriages, more passenger comfort…
Other railways kept 4’ 8½’’ !!!

37. What happened?
GWR eventually gave up and converted all their tracks back to the standard gauge…

38. What happen then?
If the Great western Railway couldn’t change a standard
…. no-one could!
Most railways around the world still use 4’ 8½
Modern space rockets transported on 4’ 8½’’ track

39. Lessons from this story
Large, powerful organisations try to make their own standards universal
Existing standards difficult to change
Once established, standards may well be adopted world-wide
therefore need to be right!

40. Standards Today…
Would a modern-day Great Western Railway have their own way?
Maybe… if an International committee agreed with them (de jure)
IETF… best ever standards body?

41. Lessons from this story
Large, powerful organisations try to make their own standards universal
Existing standards difficult to change
Once established, standards may well be adopted world-wide
therefore need to be right!

42. Standards Today… Often market-driven?
Would a modern-day GWR have their own way?