Virtual Memori (Memori Maya)

Apa itu Virtual Memori?

Mungkin sebagian dari pengguna Microsoft Windows sudah tidak asing lagi dengan istilah itu. Kerana sering sekali windows memberi peringatan kepada user tentang “Memory is low”, ini terjadi kerana komputer kekurangan memori untuk menjalankan sebuah program. Hal ini sering terjadi pada saat komputer ingin menjalankan program yang memerlukan sumber memori yang besar seperti Game, mungkin banyak gamer sering sekali terganggu dengan masalah seperti ini.

Pengertian dari Virtual Memory itu sendiri ialah Memori Sementara yang digunakan komputer untuk menjalankan berbagai program aplikasi ataupun menyimpan data yang memerlukan memory yang lebih besar dari memory yang telah tersedia ( Memory fisik seperti RAM). Program ataupun data yang tidak muat dimasukan pada memory asli ( RAM ), akan disimpan ke dalam sebuah Pagging File.

Sesuai dengan namanya “Virtual Memori” berarti :

• Memori            : Ruang penyimpanan
• Virtual              : Tiruan / tidak nyata.

Jadi Virtual Memori adalah sebuah sistem yang digunakan oleh sistem operasi untuk menggunakan sebagian dari Memori Sekunder yaitu Harddisk seolah-olah ia menggunakannya sebagai memori internal/utama (RAM) fisik yang terpasang di dalam sebuah sistem komputer. Sistem ini beroperasi dengan cara memindahkan beberapa kode yang tidak diperlukan ke sebuah berkas di dalam hard drive yang disebut dengan page file.

Pengertian Pagging file

Pagging File ialah data yang hanya disimpan sementara atau disebut swap. Pada sistem operasi linux kita diharuskan untuk membuat dua partition utama iaitu untuk system dan untuk swap. Virtual Memory ini berbeza dengan Memory fisik seperti RAM, kerana RAM merupakan komponen yang termasuk kedalam golongan hardware.

Keuntungan menggunakan Virtual Memory ini:

• Lalu lintas dari proses input dan output akan menjadi lebih rendah, sehingga proses lebih cepat
• Penggunaan memory fisik akan lebih sedikit
• Tidak akan terjadi deadlock (error system)
• Dapat menambah jumlah user yang akan ditangani
• Memory Virtual dapat diset melebihi kapasiti memory Fisik

Proses pemakaian Virtual memori di windows umumnya dapat dilihat di Task manager, seperti gambar di bawah ini.

Dalam sistem operasi berbasis Windows NT, terdapat sebuah komponen yang mengatur memori virtual yaitu Virtual Memory Manager (VMM) yang memiliki fungsi untuk dapat memetakan alamat-alamat virtual yang dimiliki oleh sebuah proses yang berjalan ke dalam page memori fisik di dalam komputer. Dengan cara ini maka setiap proses dapat memperoleh memori virtual yang cukup agar dapat berjalan dan tidak mengganggu memori yang sedang digunakan oleh proses lainnya. VMM menangani paging antara RAM dan page file agar setiap aplikasi 32-bit dapat mengakses memori hingga 4 Gigabyte, meskipun Windows hanya membatasinya pada kisaran 2 Gigabyte.

Jadi, untuk komputer yang mempunyai memori / RAM kecil ada baiknya memperbesar virtual memori agar tetap dapat menjalankan aplikasi yang memerlukankan memori yang besar terutama untuk game.

Berikut adalah langkah-langkah untuk memperbesar virtual memori di Windows XP (Experience):

1. click tombil start.
2. Pilih / masuk ke control panel.
3. Click pilihan System.
4. Maka muncul window “System properties”. Dan pilih tab Advanced
5. click tombol Setting pada frame Performance.
6. Maka  muncul window “Performance Option”. Dan pilih tab Advanced
7. kemudian click tombol Change pada  frame Virtual Memory.
8. Maka akan muncul gambar dibawah ini.

9. Ubahlah nilai yang saya lingkari menjadi lebih besar dari nilai default/ nilai standar, minimal sesuai dengan nilai yang ada di gambar ini. Yaitu berkisar antara 1024 – 2048 Megabyte.

10. Click butang Set dan OK.

11. Jika Windows anda memerlukan restart maka click butang ok dan restart komputer anda.

Sebenarnya konsep virtual memory ini juga berlaku untuk Sistem operasi lainnya seperti pada sistem operasi Linux, pada sistem operasi linux konsep virtual memory ini lebih dikenal dengan Swap memory yang telah dipartisi sebelumnya. Ini berlaku untuk semua distro linux seperti: redhat (fedora core), ubuntu/debian, mandriva/mandrake , suse dan lainnya. Tetapi dalam sistem operasi linux biasanya virtual memory telah di tetapkan sebelum proses installation-nya iaitu dalam bentuk partition harddisk untuk swap memory.

Usbehci.sys Is Needed

The process EHCI eUSB Miniport Driver belongs to the software Microsoft USB 2.0 Enhanced Host Controller Miniport Driver by Microsoft Corporation (http://www.microsoft.com/).

Description: File usbehci.sys is located in the folder C:\Windows\System32\drivers. Known file sizes on Windows XP are 26,624 bytes (36% of all occurrence), 25,216 bytes, 19,328 bytes, 19,072 bytes, 30,208 bytes, 18,816 bytes, 27,264 bytes, 27,008 bytes.
The driver can be started or stopped from Services in the Control Panel or by other programs. The program is not visible. There is no detailed description of this service. It is a trustworthy file from Microsoft. usbehci.sys seems to be a compressed file. Therefore the technical security rating is 7% dangerous, however also read the users reviews.

Download here: http://members.driverguide.com/driver/detail.php?driverid=123003

NTLDR is Missing

NTLDR is Missing

What is NTLDR?

Short for NT loader, NTLDR is a program loaded from the hard drive boot sector that displays the Microsoft Windows NT startup menu and helps Microsoft Windows NT/2000/XP load. This portion of the boot sequence was replaced by Bootmgr in Windows Vista and later versions of Windows.

 

Related errors

Below are the full error messages that may be seen when the computer is booting.

NTLDR is Missing
Press any key to restart

Boot: Couldn't find NTLDR
Please insert another disk

NTLDR is missing
Press Ctrl Alt Del to Restart

Causes

1. Computer is booting from a non-bootable source.
2. Computer hard disk drive is not properly setup in BIOS.
3. Corrupt NTLDR and NTDETECT.COM file.
4. Misconfiguration with the boot.ini file.
5. Attempting to upgrade from a Windows 95, 98, or ME computer that is using FAT32.
6. New hard disk drive being added.
7. Corrupt boot sector / master boot record.
8. Seriously corrupted version of Windows 2000 or Windows XP.
9. Loose or Faulty IDE/EIDE hard disk drive cable.
10. Failing to enable USB keyboard support in the BIOS.

Solutions

Computer is booting from a non-bootable source;

Many times this error is caused when the computer is attempting to boot from a non-bootable floppy disk or CD-ROM. First verify that no floppy diskette or CD is in the computer, unless you are attempting to boot from a diskette.

Note: This error has also been known to occur when a memory stick is in a card reader and the computer is attempting to boot from it. If you have any card reader or flash reader make sure that no memory stick is inside the computer. Additionally disconnect all USB drives, cameras, ipods, iphones, etc. from the computer.

If you are attempting to boot from a floppy diskette and are receiving this error message it is likely that the diskette does not have all the necessary files or is corrupt.

If you are attempting to install Windows XP or Windows 2000 and are receiving this error message as the computer is booting verify that your computer BIOS has the proper boot settings. For example, if you are attempting to run the install from the CD-ROM make sure the CD-ROM is the first boot device, and not the hard disk drive.

Second, when the computer is booting you should receive the below prompt.

Press any key to boot from the CD

Important: When you see this message press any key such as the Enter key immediately, otherwise it will try booting from the hard drive and likely get the NTLDR error again.

Note: If you are not receiving the above message and your BIOS boot options are set properly it's also possible that your CD-ROM drive may not be booting from the CD-ROM properly. Verify the jumpers are set properly on the CD-ROM drive.

Computer hard disk drive is not properly setup in BIOS;

Verify that your computer hard disk drive is properly setup in the CMOS setup. Improper settings can cause this error.

Corrupt NTLDR or NTDETECT.COM file;

Windows 2000 users
Windows XP users

Windows 2000 users

If your computer is using Microsoft Windows 2000 and you are encountering the NTLDR error. Create the below boot.ini file on the floppy diskette drive.

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 2000 Professional" /fastdetect

Copy the NTLDR and NTDETECT.COM files from another computer using the same operating system. Both of these files are located in the root directory of the primary hard disk drive. For example, C:\NTLDR and C:\NTDETECT.COM should be the locations of these files on many computers.

• How do I view hidden files in Windows?

Once these files have been copied to a floppy diskette reboot the computer and copy the NTLDR and NTDETECT.COM files to the root directory of the primary hard disk drive. Below is an example of what commonly should be performed from the A:\> drive.

copy ntldr c:
copy ntdetect.com c:

After the above two files have been copied, remove the floppy diskette and reboot the computer.

Windows XP users

1. Insert the Windows XP bootable CD into the computer.
2. When prompted to press any key to boot from the CD, press any key.
3. Once in the Windows XP setup menu press the "R" key to repair Windows.
4. Log into your Windows installation by pressing the "1" key and pressing enter.
5. You will then be prompted for your administrator password, enter that password.
6. Copy the below two files to the root directory of the primary hard disk. In the below example we are copying these files from the CD-ROM drive letter, which in this case is "e." This letter may be different on your computer.
   
   copy e:\i386\ntldr c:\
   copy e:\i386\ntdetect.com c:\
7. Once both of these files have been successfully copied, remove the CD from the computer and reboot.

Misconfiguration with the boot.ini file;

Edit the boot.ini on the root directory of the hard disk drive and verify that it is pointing to the correct location of your Windows operating system and that the partitions are properly defined.

Attempting to upgrade from a Windows 95, 98, or ME computer that is using FAT32;

If you are getting this error message while you are attempting to upgrade to Windows 2000 or Windows XP from Windows 95, Windows 98, or Windows ME running FAT32 try the below recommendations.

1. Boot the computer with a Windows 95, Windows 98 or Windows ME bootable diskette.
2. At the A:\> prompt type:
   
   sys c: <press enter>
3. After pressing enter you should receive the "System Transferred" message. Once this has been completed remove the floppy diskette and reboot the computer.

New hard disk drive being added;

If you are attempting to add a new hard disk drive to the computer make sure that drive is a blank drive. Adding a new hard disk drive to a computer that already has Windows installed on it may cause the NTLDR error to occur.

If you are unsure if the new drive is blank or not try booting from a bootable diskette and format the new hard disk drive.

Corrupt boot sector / master boot record;

It's possible your computer's hard disk drive may have a corrupt boot sector or master boot record. These can be repaired through the Microsoft Windows Recovery console by running the fixboot and fixmbr commands.

Seriously corrupted version of Windows 2000 or Windows XP;

If you have tried each of the above recommendations that apply to your situation and you continue to experience this issue it is possible you may have a seriously corrupted version of Microsoft Windows. Therefore we would recommend you reinstall Microsoft Windows 2000 and Windows XP.

If you are encountering this issue during your setup you may wish to completely erase your computer hard disk drive and all of its existing data and then install Microsoft Windows.

Loose or Faulty IDE/EIDE hard disk drive cable;

This issue has been known to be caused by a loose or fault IDE/EIDE cable. If the above recommendation does not resolve your issue and your computer hard disk drive is using an IDE or EIDE interface. Verify the computer hard disk drive cable is firmly connected by disconnected and reconnecting the cable.

If the issue continues it is also a possibility that the computer has a faulty cable, try replacing the hard disk drive cable with another cable or a new cable.

How to Enable a USB Port - Bagaimana Untuk Mengaktifkan USB Port

The Universal Serial Bus (USB) is an extremely popular computer hardware interface introduced sometime in 1995 to provide computer users with a way of attaching secondary hardware devices that capitalize on the Plug-and-Play functionality of the Operating System. By 1997, almost every new computer system that rolled out of the assembly line was equipped with a USB port which was already supported as early as the Microsoft Windows 98 Operating System platform and has since then replaced all other connectivity standards. One USB port allows for the connection of literally hundreds of interchangeable devices like keyboards, modems, joysticks, mouse pointing devices, printers, external storage, digital cameras, and scanners among others. The presence of the USB port boosted the popularity of Plug-and-Play and has been closely associated with the term hot swappable which referenced devices that can be connected and disconnected without requiring the computer system to be turned off or rebooted.

Universal Serial Bus (USB) adalah sebuah komputer yang sangat popular diperkenalkan suatu antara muka hardware pada tahun 1995 untuk memberikan pengguna komputer dengan cara melampirkan peranti keras sekunder yang memanfaatkan fungsi Plug-and-Play Sistem Operasi. Pada tahun 1997, hampir setiap sistem komputer baru yang berguling keluar dari pusat perakitan dilengkapi dengan port USB yang sudah disokong awal sebagai platform Microsoft Windows 98 Sistem Operasi dan sejak itu diganti semua standard kesambungan yang lain. Satu port USB yang membolehkan untuk sambungan ratusan peranti dipertukarkan seperti keyboard, modem, joystick, mouse menunjuk peranti, printer, simpanan luaran, kamera digital, dan scanner antara lain. Kewujudan port USB meningkatkan populariti Plug-Play dan-dan telah erat berkaitan dengan hot swappable istilah yang dirujuk peranti yang boleh dihubungkan dan ditamatkan tanpa memerlukan sistem komputer dimatikan atau reboot.


Materials Needed:

- Computer with USB port
- Microsoft Windows XP Operating System
- motherboard documentation

Step 1

In some instances, in order to prevent unauthorized copying of data to USB-based storage devices, the USB port is disabled intentionally. To enable the USB port, click on the 'Start' button and right click on the 'My Computer' option.

Step 2

Choose the 'Manage' option from the context menu to open the Computer Management window. Click on the 'System Tools' category on the left panel. This will display all connected devices of the computer system at the right panel.

Step 3

Click on the '+' sign beside the Universal Serial Bus controllers option to expand it. Right click on the USB Root hub and select 'Enable'.

Step 4

Click on the 'File' menu and select 'Exit' to close the Computer Management window. Reboot the computer system to make sure the changes take effect.

Step 5

An alternative method for the Microsoft Windows environment is to click on the 'Start' button and select the 'Control Panel' option.

Step 6

Click on the 'Performance and Maintenance' category and select the 'System' option. This will open the System Properties window.

Step 7

Choose the 'Hardware' tab and click the 'Device Manage' button. In the Device Manager window, expand the option for the Universal Serial Bus category.

Step 8

Select the USB Root hub entry and click on the 'Enable' icon on the toolbar at the upper part of the Device Manager window. Click on the 'File' menu and select 'Exit'.

Step 9

To enable the USB port from the Windows Registry, click on the 'Start' button and select the 'Run' option.

Step 10

Type regedit in the Open box and click on the 'OK' button to bring up the Registry Editor window.

Step 11

Expand the SYSTEM category under HKEY_LOCAL_MACHINE. Click on the '+' beside CurrentControlSet and choose Services.

Step 12

Click the UsbStor option. This should display a list of registry keys in the right pane window. Double click on the 'Start' key and replace its value with 3. Make sure that Hexadecimal is selected.

Step 13

Click on the 'OK' button. Exit the Registry Editor to complete the process of enabling the USB port.

Step 14

A more direct method is to reboot the computer system and enter the BIOS setting configuration window. Refer to the motherboard’s documentation to identify how to access the BIOS settings and enable the USB port.