operating systems university of moratuwa department of electronic and telecommunication engineering...

Operating Systems

University of Moratuwa

Department of Electronic and Telecommunication Engineering

Short Course on Computer Hardware and Assembly July 16, 2002

Dr. E.C. Kulasekere

What's Next?




• Assembled computer available.

• Choice of right tool to integrate.

• Should we use a screwdriver to pound nails into the wall?

• Any guidelines to choose the right tool?

Operating System Selection




• Single or Multiple OSs?

• Type of OS; Microsoft-style or Unix-style?

• Matching the OS to your ability, application software need and urgency of use.

Multi-OS System




• Leave plenty of space.

• Consider running an Emulator.

• Setup data exchange between OSs.

• Investigate Hardware needs.

• Drivers available for current hardware?

Hardware Compatibility Issues




• The Motherboard.

• I/O and peripheral cards.

• The CPU and its performance.

• Memory capacity adequate?

• Mass storage devices.

• Multimedia compatibility.

Expectations From a New OS




• Give yourself adequate time.

• Research what problems need to be solved.– Software based.– Stability of OS.– Curiosity

• Expect a learning curve.

OS Installation Basics




• Disk Partitioning.– Shared partition?– In separate partitions?

• Partition types.– Primary partitions– Extended partitions.– Logical partitions

OS’s for x86 Hardware




• DOS variants.

• Windows 9x.

• Windows NT/2000.

• Unix variants.

Any advantages of using a particular OS?

Windows 9x




• Introduced 32 Bit support.• Requires at least a 386 computer.• Does preemptive multitasking.• VFAT extension with long filenames.• FAT32 support.• Tighter network integration.• Boot into a GUI.

When to Move on




• Internal and External security is lax.

• Multi-user configuration is primitive.

• Questionable stability.

• DOS based OS core.

• Low performance compared to NT and UNIX.

Windows NT/2000




• 32-Bit multitasking kernel.

• Works on non-Intel platforms.

• NTFS which is faster and more reliable than FAT is introduced.

• Improved multi-tasking and networking.

• User access control.

When to Move on




• Imperfect 16-Bit support.

• NTFS incompatibility with most other OSs.

• Reduced hardware support (Windows 2000 rectifies this).

• Concurrent multi-user performance is low.

Linux




• Open source and free.

• Robust multi-tasking environment.

• Excellent networking capabilities.

• Customizable X-windows GUI.

• Excellent, stable multi-user capabilities.

When to Move on




• Steep learning curve.

• Open source results in network security problems.

• Limited number of end-user applications.

• Poor hardware support.

The Boot Process



Short Course on Computer Hardware and Assembly April 18, 2023

• Multi OSs should be coaxed to boot.

• BIOS as a boot loader.

• Methods the boot loaders work in multi OS systems.

BIOS History




• 16-Bit and 32-Bit addressing and the BIOS.

• BIOS interface with low level Hardware.

• BIOS as a POST and boot handoff.

• CMOS and PnP uses of BIOS.

BIOS Types




• AMI BIOS, Phoenix BIOS, Award BIOS.

• Add on BIOS cards.

• Video BIOS.

• SCSI BIOS.

• Sound and Multimedia hardware BIOS.

BIOS Updates




• Rewriting EEPROM or Flash BIOS.

• Upgrades eliminate bugs.

• Upgrades add improvements.

• Process is extremely dangerous.

• May result in an unbootable system.

• Sketch of finding and upgrading.

BIOS and Hard Disks




• The connection to OS installation.

• Motherboard BIOS controls EIDEs.

• SCSI Hard Disks are controlled by SCSI BIOS.

• What is CHS disk geometry?

The Modern Hard Disk




The Hard Disk




• Rotational speed is important.

• Head reads typically 512 Bytes at a time.

• Cylinder, head, sector---CHS

• BIOS reads the CHS to understand address of boot loader.

The 1024 Cylinder Limit




• Result of bit allocation for the CHS geometry in the BIOS.

• At Boot time only the 1024 cylinders are seen

• OS loader should be within this limit to load.

• In olden computers the limit on hard disk capacity is 540 MB.

Getting around 1024 limit




• Ignore it. Make sure the boot loader is within the 1024 cylinders. Eg. Linux

• CHS geometry translation carried out in the hard disk controller. Total drive capacity remains the same.

• SCSI uses LBA which has one 28-bit sector number.

Boot Loader – Single OS




Boot Loader – Multi-OS




Types of Boot Loaders




• Floppy based. Eg. Linux. Can be used to check a new OS.

• MBR-Based. Popular but can be destroyed by other OS installation

• Boot sector- based. Less susceptible to be destructed with new installations.

Common Boot-loaders




• NT-loader.

• Linux LILO.

• System commander.

• Boot magic.

Uses of Partitioning




• TO save space. Eg. FAT16 partition sizes should be less than 511MB.

• Easier disaster recovery.

• Location of data can be positioned so that hard drive seek is easier and head wear is minimum.

Tools for Partitioning




• FDISK. For DOS and Linux

• Windows NT disk administrator

• PartitionMagic.

• FIPS.

FDISK (DOS)




• Tightly coupled with the partition type. • Primary should be created before

extended. • Unable to create more than one primary.• Partition placement is not allowed. The

allocation is automatic.• Unable to cope with non-FAT partitions.

NT Disk Admin




• Graphical user interface.

• Can create multiple primary partition.

• Can create a logical partition without a primary partition.

• Can delete non-FAT partitions.

PartitionMagic




• Graphical user interface.• Can create multiple primary partition.• Can create a logical partition without a

primary partition.• Can delete non-FAT partitions.• Create file system.• Moving and resizing partitions.• Copying and converting partitions.

Partition Formatting




• Low-level:--Erases the data and file system structure. Takes time. Rebuilds the disk structures.

• High-level:--Basic structure like boot sector and root directory are created. Takes a short time.

When to modify and repartition?




• Adding an OS.

• Deleting an OS.

• Shifting disk space requirement.

• Adding a new hard disk.

Consequences of Repartitioning




• Drive letter changes: Software becomes unusable. Extreme cases the OS becomes unbootable.

• UNIX device identifier changes: mount points can change and the OS becoming unbootable. Change /etc/fstab to reflect changes.

When to modify and repartition?




• Adding an OS.

• Deleting an OS.

• Shifting disk space requirement.

• Adding a new hard disk.

Optimizing Partitions




• Outer most part of a disk platter is faster than the inner most platter in a hard disk.

• Applications that need best performance should be placed first. Eg. Swap space, most frequently used programs, large data files.

Dangers of Too Many Partitions




Increased head movement can damage hard disk

Installing the OS




• Microsoft OSs copy the installation files to hard disk for optimal performance.

• For UNIX OSs choose the partitions appropriately so that disaster recovery can be easier. Choose appropriate code changes. Position the /boot below 1024 cylinders or use a floppy.

• Install MS OS before anything else since it damages other OSs.

Installation Problems




• If the system is unbootable, use a floppy to boot into the system and make changes. Do not reinstall as a first option.

• Have the data in a shared partition.

operating systems university of moratuwa department of electronic and telecommunication engineering...

Documents

computer hardware

current hardware

hardware needs

kulasekere slide

assembled computer available

stability of os

particular os

os core