Created By: Hussein Nosair

Source: How to upgrade from CDE 1.0.0.43 BETA to 1.2.46.58 BETA

How To Fix MBR using Windows Vista Bootable Disk?
———————————————————————————

Step 1) Boot up your computer using Microsoft Windows Vista Bootable disk. (Check your BIOS setup)
Step 2) When you see the 1st Windows Vista installation screen appear, please configure your ‘language’ preferences.
Step 3) When prompted, click ‘Repair your computer’.
Step 4) Click Command Prompt from the System Recovery Options.
Step 5) Run "BootRec /FixMbr".
Step 6) This command re-writes the master boot record (MBR) of the system partition to start Windows Vista. This won’t overwrite the existing partition table.

How To Fix MBR using Windows XP Bootable Disk?
———————————————————————————

Step 1) Boot up your computer using Microsoft Windows XP Bootable disk. (Check your BIOS setup)
Step 2) When you the first Windws Xp installation screen appears, select "Repair a Windows XP installation using Recovery Console" by pressing ‘R’.
Step 3) In that command prompt screen type "FIXMBR".
Step 4) This command re-writes the master boot record (MBR) of the system partition to start Windows XP. This won’t overwrite the existing partition table.

Created By: Hussein Nosair

This is my attempt to create a spur gear in Autocad.

Created By: Hussein Nosair

Solution

PADS 9.0 and newer:
Beginning with PADS 9.0 there is native IPC netlist extract capability.  Go to File > Export and change the "Files of Type" from ASCII Files (*.asc) to IPC 356 Files (*.ipc).  After clicking save you will be able to choose between IPC-D-356 or IPC-D-356A netlist output.
PADS2007.4 and older:

The older versions of PADS do not have native IPC netlist extraction.  However, you can download a VB script that has been written by a 3rd party vendor at CapeCAD.com (note, the VB script has not been tested by Mentor Graphics and we assume no responsibility for it’s accuracy).

Created By: Hussein Nosair 

Solution

Method1:1) Open your schematic in PADS Logic
2) Go tools > select PADS Layout > You will get ‘Connect to PADS Layout’ popup menu > click on Open > Navigate to modified PCB Design file > click Open.
3) The selected PCB design file will open in another PADS Layout window (keep it open).
4) Select PADS Logic window
5) Within the ‘PADS Layout link’ popup menu > click on the Design tab > click on ‘ECO from PCB’

This will update the changes of PADS Layout into PADS Logic

Method2:1) Open your PCB design file in PADS Layout
2) Go tools > Compare/ECO > you will get Compare/ECO Tools popup window
3) Click on the Documents tab > Add a check mark next to "Original Design to Compare and Update" and navigate schematic netlist file.
4) Then from "New Design with Changes" , click "Use Current PCB Design".
5) From the ‘Output Options’ add a check mark next to "Generate Difference Report" and "Generate ECO File"
6) Note down the location of ECO file then is going to be generated and click on the button ‘RUN’
7) Open PADS Logic
Invoke Schematic file.
9) Go to File > Import > will get ‘File Import’ popup menu
10) Within the popup menu select ‘Files of Type’ as ECO Files (*.eco) and navigate the .eco file which is generated from the PADS Layout > Click open.

This imports the changes of PADS Layout into PADS Logic.

Note for back annotation of renumbered Reference Designators:
    The PADS Layout Link in PADS Logic or creating an ECO file by using Tools > Compare/ECO in PADS Layout will not result in a correct reference designator update; this is particularly true for discrete devices.
    To pass ref des renumbering back to Logic you must specify that an ECO file be created in ECO Options prior to using the Auto-Renumber function in PADS Layout. When you open the ECO toolbar in PADS Layout take note that the "Write ECO file" box is checked, the "Append to file" is unchecked, the "Write ECO file after closing ECO toolbar" is checked and what location the ECO file is being written to. Once the renumbering is complete and you exit from the ECO toolbar the ECO file that was created will then be used in PADS Logic by going to File > Import (change Files of Type to *.eco).
    Logging the ECO file in this manner creates an exact list of the reference designators, recording the current reference designator and the new reference designator that corresponds to it after renumbering.  Note: Make sure that the designs are synchronized prior to performing the auto renumbering procedure.

Solution

This will update all parts on the board with information contained in the library.

1. Open the PADS Layout file you wish to update.
2. Go to File>Export (you will be exporting an ASCII file).
3. Select a file name and location to save your ASCII file to, click Save.
4. The ASCII Output dialog box will appear.
5. Click on the ‘Select All’ button.
6. Remove the check mark from Decals and Packages, click OK.
7. Go to File>New (Save the file if you have made changes, otherwise select No).
8. If prompted with a ‘Set Start-up File’ dialog box select the System Default Start-up File.
9. Go to File>Import.
10. Browse to the location of the ASCII file created in step three, click Open.
11. The file will read in and update all parts on the board with the information contained in the library.

Make sure that your library contains all the necessary part types and PCB decals for the board.

Note 1: This process will update the PCB decals, but will not update Part type information such as attributes or alphanumeric pins.
Note 2: When a decal’s pad stacks are modified and only the Selected component is updated then the decal name is appended with an "a".  If the design database contains modified decals like this the update process may fail for those decals unless they exist in the library.

Created By: Hussein Nosair

Schematic:

Pspice Model of Schematic:

*TVS Simulation Circuit

**************************************************
** Littelfuse P4KE12A, TVS, uni-directional     **
**                                              **
** ITC, 04/09/05                                **
**************************************************
.SUBCKT P4KE24A  1   2
*    TERMINALS:  A   K
Dpri  1 3 Dtvs
Rleak 1 3 13meg
Lind  3 2 2e-15
.MODEL Dtvs D (RS=0.05 N=1.5 IBV=1m BV=24.0 CJO=450p)
.ENDS

Vin 0 1 24V
Rs     1 2 5
X1     0 2 P4KE24A
RL     2 0 1k

.DC Vin 0 100 1
.TRAN 40E-6 3E-3
.PRINT TRAN V(2) I(Rs) I(RL)
.PROBE
.OPTIONS NOPAGE
.END

Pspice Model Results in Normal Operation:

**** 07/04/09 01:14:56 ******* PSpice *********

*TVS Simulation Circuit

****     CIRCUIT DESCRIPTION

******************************************************************************

**************************************************
** Littelfuse P4KE12A, TVS, uni-directional     **
**                                              **
** ITC, 04/09/05                                **
**************************************************
.SUBCKT P4KE24A  1   2
*    TERMINALS:  A   K
Dpri  1 3 Dtvs
Rleak 1 3 13meg
Lind  3 2 2e-15
.MODEL Dtvs D (RS=0.05 N=1.5 IBV=1m BV=24.0 CJO=450p)
.ENDS

Vin     1 0 24V
Rs      1 2 5
X1      0 2 P4KE24A
RL      2 0 1k

.DC Vin 0 100 1
.TRAN 40E-6 3E-3
.PRINT TRAN V(2) I(Rs) I(RL)
.PROBE
.OPTIONS NOPAGE
.END

****     Diode MODEL PARAMETERS

               X1.Dtvs        
          IS   10.000000E-15
           N    1.5         
          BV   24           
         IBV    1.000000E-03
          RS     .05        
         CJO  450.000000E-12

****     INITIAL TRANSIENT SOLUTION       TEMPERATURE =   27.000 DEG C

NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE

(    1)   24.0000  (    2)   23.8810  ( X1.3)   23.8810 

    VOLTAGE SOURCE CURRENTS
    NAME         CURRENT

    Vin         -2.389E-02

    TOTAL POWER DISSIPATION   5.73E-01  WATTS

****     TRANSIENT ANALYSIS               TEMPERATURE =   27.000 DEG C

  TIME        V(2)        I(Rs)       I(RL)      

   0.000E+00   2.388E+01   2.389E-02   2.388E-02
   4.000E-05   2.388E+01   2.389E-02   2.388E-02
   8.000E-05   2.388E+01   2.389E-02   2.388E-02
   1.200E-04   2.388E+01   2.389E-02   2.388E-02
   1.600E-04   2.388E+01   2.389E-02   2.388E-02
   2.000E-04   2.388E+01   2.389E-02   2.388E-02
   2.400E-04   2.388E+01   2.389E-02   2.388E-02
   2.800E-04   2.388E+01   2.389E-02   2.388E-02
   3.200E-04   2.388E+01   2.389E-02   2.388E-02
   3.600E-04   2.388E+01   2.389E-02   2.388E-02
   4.000E-04   2.388E+01   2.389E-02   2.388E-02
   4.400E-04   2.388E+01   2.389E-02   2.388E-02
   4.800E-04   2.388E+01   2.389E-02   2.388E-02
   5.200E-04   2.388E+01   2.389E-02   2.388E-02
   5.600E-04   2.388E+01   2.389E-02   2.388E-02
   6.000E-04   2.388E+01   2.389E-02   2.388E-02
   6.400E-04   2.388E+01   2.389E-02   2.388E-02
   6.800E-04   2.388E+01   2.389E-02   2.388E-02
   7.200E-04   2.388E+01   2.389E-02   2.388E-02
   7.600E-04   2.388E+01   2.389E-02   2.388E-02
   8.000E-04   2.388E+01   2.389E-02   2.388E-02
   8.400E-04   2.388E+01   2.389E-02   2.388E-02
   8.800E-04   2.388E+01   2.389E-02   2.388E-02
   9.200E-04   2.388E+01   2.389E-02   2.388E-02
   9.600E-04   2.388E+01   2.389E-02   2.388E-02
   1.000E-03   2.388E+01   2.389E-02   2.388E-02
   1.040E-03   2.388E+01   2.389E-02   2.388E-02
   1.080E-03   2.388E+01   2.389E-02   2.388E-02
   1.120E-03   2.388E+01   2.389E-02   2.388E-02
   1.160E-03   2.388E+01   2.389E-02   2.388E-02
   1.200E-03   2.388E+01   2.389E-02   2.388E-02
   1.240E-03   2.388E+01   2.389E-02   2.388E-02
   1.280E-03   2.388E+01   2.389E-02   2.388E-02
   1.320E-03   2.388E+01   2.389E-02   2.388E-02
   1.360E-03   2.388E+01   2.389E-02   2.388E-02
   1.400E-03   2.388E+01   2.389E-02   2.388E-02
   1.440E-03   2.388E+01   2.389E-02   2.388E-02
   1.480E-03   2.388E+01   2.389E-02   2.388E-02
   1.520E-03   2.388E+01   2.389E-02   2.388E-02
   1.560E-03   2.388E+01   2.389E-02   2.388E-02
   1.600E-03   2.388E+01   2.389E-02   2.388E-02
   1.640E-03   2.388E+01   2.389E-02   2.388E-02
   1.680E-03   2.388E+01   2.389E-02   2.388E-02
   1.720E-03   2.388E+01   2.389E-02   2.388E-02
   1.760E-03   2.388E+01   2.389E-02   2.388E-02
   1.800E-03   2.388E+01   2.389E-02   2.388E-02
   1.840E-03   2.388E+01   2.389E-02   2.388E-02
   1.880E-03   2.388E+01   2.389E-02   2.388E-02
   1.920E-03   2.388E+01   2.389E-02   2.388E-02
   1.960E-03   2.388E+01   2.389E-02   2.388E-02
   2.000E-03   2.388E+01   2.389E-02   2.388E-02
   2.040E-03   2.388E+01   2.389E-02   2.388E-02
   2.080E-03   2.388E+01   2.389E-02   2.388E-02
   2.120E-03   2.388E+01   2.389E-02   2.388E-02
   2.160E-03   2.388E+01   2.389E-02   2.388E-02
   2.200E-03   2.388E+01   2.389E-02   2.388E-02
   2.240E-03   2.388E+01   2.389E-02   2.388E-02
   2.280E-03   2.388E+01   2.389E-02   2.388E-02
   2.320E-03   2.388E+01   2.389E-02   2.388E-02
   2.360E-03   2.388E+01   2.389E-02   2.388E-02
   2.400E-03   2.388E+01   2.389E-02   2.388E-02
   2.440E-03   2.388E+01   2.389E-02   2.388E-02
   2.480E-03   2.388E+01   2.389E-02   2.388E-02
   2.520E-03   2.388E+01   2.389E-02   2.388E-02
   2.560E-03   2.388E+01   2.389E-02   2.388E-02
   2.600E-03   2.388E+01   2.389E-02   2.388E-02
   2.640E-03   2.388E+01   2.389E-02   2.388E-02
   2.680E-03   2.388E+01   2.389E-02   2.388E-02
   2.720E-03   2.388E+01   2.389E-02   2.388E-02
   2.760E-03   2.388E+01   2.389E-02   2.388E-02
   2.800E-03   2.388E+01   2.389E-02   2.388E-02
   2.840E-03   2.388E+01   2.389E-02   2.388E-02
   2.880E-03   2.388E+01   2.389E-02   2.388E-02
   2.920E-03   2.388E+01   2.389E-02   2.388E-02
   2.960E-03   2.388E+01   2.389E-02   2.388E-02
   3.000E-03   2.388E+01   2.389E-02   2.388E-02

          JOB CONCLUDED

****     JOB STATISTICS SUMMARY

  Total job time (using Solver 1)   =         .02

Pspice Model Results in Reversed Polarity of Vin:

**** 07/04/09 01:17:08 ******* PSpice *********

*TVS Simulation Circuit

****     CIRCUIT DESCRIPTION

******************************************************************************

**************************************************
** Littelfuse P4KE12A, TVS, uni-directional     **
**                                              **
** ITC, 04/09/05                                **
**************************************************
.SUBCKT P4KE24A  1   2
*    TERMINALS:  A   K
Dpri  1 3 Dtvs
Rleak 1 3 13meg
Lind  3 2 2e-15
.MODEL Dtvs D (RS=0.05 N=1.5 IBV=1m BV=24.0 CJO=450p)
.ENDS

Vin     0 1 24V
Rs      1 2 5
X1      0 2 P4KE24A
RL      2 0 1k

.DC Vin 0 100 1
.TRAN 40E-6 3E-3
.PRINT TRAN V(2) I(Rs) I(RL)
.PROBE
.OPTIONS NOPAGE
.END

****     Diode MODEL PARAMETERS

               X1.Dtvs        
          IS   10.000000E-15
           N    1.5         
          BV   24           
         IBV    1.000000E-03
          RS     .05        
         CJO  450.000000E-12

****     INITIAL TRANSIENT SOLUTION       TEMPERATURE =   27.000 DEG C

NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE     NODE   VOLTAGE

(    1)  -24.0000  (    2)   -1.5335  ( X1.3)   -1.5335 

    VOLTAGE SOURCE CURRENTS
    NAME         CURRENT

    Vin         -4.493E+00

    TOTAL POWER DISSIPATION   1.08E+02  WATTS

****     TRANSIENT ANALYSIS               TEMPERATURE =   27.000 DEG C

  TIME        V(2)        I(Rs)       I(RL)      

   0.000E+00  -1.534E+00  -4.493E+00  -1.534E-03
   4.000E-05  -1.534E+00  -4.493E+00  -1.534E-03
   8.000E-05  -1.534E+00  -4.493E+00  -1.534E-03
   1.200E-04  -1.534E+00  -4.493E+00  -1.534E-03
   1.600E-04  -1.534E+00  -4.493E+00  -1.534E-03
   2.000E-04  -1.534E+00  -4.493E+00  -1.534E-03
   2.400E-04  -1.534E+00  -4.493E+00  -1.534E-03
   2.800E-04  -1.534E+00  -4.493E+00  -1.534E-03
   3.200E-04  -1.534E+00  -4.493E+00  -1.534E-03
   3.600E-04  -1.534E+00  -4.493E+00  -1.534E-03
   4.000E-04  -1.534E+00  -4.493E+00  -1.534E-03
   4.400E-04  -1.534E+00  -4.493E+00  -1.534E-03
   4.800E-04  -1.534E+00  -4.493E+00  -1.534E-03
   5.200E-04  -1.534E+00  -4.493E+00  -1.534E-03
   5.600E-04  -1.534E+00  -4.493E+00  -1.534E-03
   6.000E-04  -1.534E+00  -4.493E+00  -1.534E-03
   6.400E-04  -1.534E+00  -4.493E+00  -1.534E-03
   6.800E-04  -1.534E+00  -4.493E+00  -1.534E-03
   7.200E-04  -1.534E+00  -4.493E+00  -1.534E-03
   7.600E-04  -1.534E+00  -4.493E+00  -1.534E-03
   8.000E-04  -1.534E+00  -4.493E+00  -1.534E-03
   8.400E-04  -1.534E+00  -4.493E+00  -1.534E-03
   8.800E-04  -1.534E+00  -4.493E+00  -1.534E-03
   9.200E-04  -1.534E+00  -4.493E+00  -1.534E-03
   9.600E-04  -1.534E+00  -4.493E+00  -1.534E-03
   1.000E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.040E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.080E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.120E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.160E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.200E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.240E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.280E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.320E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.360E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.400E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.440E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.480E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.520E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.560E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.600E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.640E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.680E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.720E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.760E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.800E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.840E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.880E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.920E-03  -1.534E+00  -4.493E+00  -1.534E-03
   1.960E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.000E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.040E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.080E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.120E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.160E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.200E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.240E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.280E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.320E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.360E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.400E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.440E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.480E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.520E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.560E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.600E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.640E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.680E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.720E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.760E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.800E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.840E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.880E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.920E-03  -1.534E+00  -4.493E+00  -1.534E-03
   2.960E-03  -1.534E+00  -4.493E+00  -1.534E-03
   3.000E-03  -1.534E+00  -4.493E+00  -1.534E-03

          JOB CONCLUDED

****     JOB STATISTICS SUMMARY

  Total job time (using Solver 1)   =         .03

Open a command-box (as administrator) and type the following;
regsvr32 "%ProgramFiles%\COMODO\COMODO Internet Security\cavshell.dll"

If you would like to unregister this and remove it from the right click context-menu type the following;
regsvr32 /u "%ProgramFiles%\COMODO\COMODO Internet Security\cavshell.dll"

Created By: Hussein Nosair 

 Zip Archived file

RAR Archived file

The above picture is schematic representation/symbol of Resistor.

Unfortunately, my schematic software (PADS LOGIC) did not have such a component in its library; so I had to build the above component from scratch.

I used AutoCAD to build the above component and I save it as AutoCAD 12 DXF file.

To download the DXF file:

1. Click on the above image

2. Right Click on the Image

3. Save the image/picture to your harddisk

Extract the DXF File:

1. open winzip/winrar

2. File > open

3. browse to the save image file

OR

1. Open WinZip

2. Drag the image and drop it off inside the WinZip software.

NOTE: If you cannot follow the above steps, please refer to the following post: Extract Files embedded in Pictures

Importing AutoCAD DXF file into PADS library:

1. Open PADS LAYOUT

2. File > Import > browse to the above DXF file.

3. Once PADS has imported the file, highlight (select everything) the above component.

4. Right click on the selected component > combine

5. Right Click on the selected component > Add to library

6. Give this new shape (component) a name.

7. Close PADS LAYOUT

And you are done.

1. Open PADS LOGIC

2. Tools > Part Editor

3. Click on Edit graphics in the Part Editor Toolbar

4. Click OK to the message

5. Hit the Page Down button a few times to zoom out the screen

6. Click on Add 2D line from Library from in the Symbol editor Toolbar

7. Locate the above drawing and click OK to add it to the screen.

Now, you just have to either add pins or create some kind of shape around the above drawing to create your own custom component.

Hussein Nosair

I found the following online and I thought that I should share this with every one to eliminate the Windows / PC crashes epidemic.

Fatal error: the system has become unstable or is busy," in this case the system, mostly windows running system, will provide options for the user to select. One of the options is to press Enter to return to Windows and wait for the current running process to finish its job or press Control-Alt-Delete to restart your computer. If you do select to restart the computer, you will lose any unsaved information in all open applications.

Another cause of windows crashing, is the you have been zapped by the Blue Screen of Death. Anyone who uses Microsoft Windows will be familiar with this. If this happens then you are out of luck to rescue any unsaved information in running application. To prevent the blue screen of death, you need to understand the cause first to prevent it from happening in the future.

Index:

1. Hardware conflict

2. Bad Ram (Memory)

3. BIOS settings

4. Hard disk drives

5. Fatal OE exceptions and VXD errors

6. Viruses

7. Printers

8. Software

9. Overheating

10. Power supply problems

1. Hardware conflict

The number one reason why Windows crashes is hardware conflict. Each hardware device communicates internally or externally with other devices. However, most of the hardware conflicts stem from internal devices.

These devices communicate with each other on a BUS through an interrupt request channel (IRQ). These are supposed to be unique numbers/addresses for each internal device.

For example, a printer usually connects internally on IRQ 7. The keyboard usually uses IRQ 1 and the floppy disk drive IRQ 6. Each device will try to hog a single IRQ for itself.

If there are a lot of devices, or if they are not installed properly, two of them may end up sharing the same IRQ number. When the user tries to use both devices at the same time, a crash can happen.

Another underline cause of windows crashing is improper installation of device driver or wrong driver is used to install a device in the system. Any addition of devices to a system, the user need to install a driver that tells the system how to interact and address the added device.

To check, if your computer has a hardware conflict is through the following route:

* Start –> Settings –> Control Panel –> System –> Device Manager.

OR

* Right click on “My Computer” icon –> Properties –> Hardware tab –> Device Manager (Windows XP)

OR

* Right click on “ My Computer” icon –> Properties –> Device Manager (Vista)

Often, if a device has a problem, a yellow ‘!’ appears next to its description in the Device Manager. Highlight Computer (in the Device Manager) and press Properties to see the IRQ numbers used by your computer. If the IRQ number appears twice, two devices may be using it.

Sometimes a device might share an IRQ with something described as ‘IRQ holder for PCI steering’. This can be ignored. The best way to fix this problem is to remove the problem device and reinstall it.

Sometimes you may have to find more recent drivers on the internet to make the device function properly. A good resource is www.driverguide.com. If the device is a soundcard, or a modem, it can often be fixed by moving it to a different slot on the motherboard (be careful about opening your computer, as you may void the warranty).

When working inside a computer you should switch it off, unplug the mains lead and touch an unpainted metal surface to discharge any static electricity.

To be fair to Microsoft, the problem with IRQ numbers is not of its making. It is a legacy problem going back to the first PC designs using the IBM 8086 chip. Initially there were only eight IRQs. Today there are 16 IRQs in a PC. It is easy to run out of them. There are plans to increase the number of IRQs in future designs.

2. Bad Ram (Memory)

Ram (random-access memory) problems might bring on the blue screen of death with a message saying Fatal Exception Error. A fatal error indicates a serious hardware problem. Sometimes it may mean a part is damaged and will need replacing.

But a fatal error caused by Ram might be caused by a mismatch of chips. For example, mixing 70-nanosecond (70ns) Ram with 60ns Ram will usually force the computer to run all the Ram at the slower speed. This will often crash the machine if the Ram is overworked.

One way around this problem is to enter the BIOS settings and increase the wait state of the Ram. This can make it more stable. Another way to troubleshoot a suspected Ram problem is to rearrange the Ram chips on the motherboard, or take some of them out. Then try to repeat the circumstances that caused the crash. When handling Ram try not to touch the gold connections, as they can be easily damaged.

Parity error messages also refer to Ram. Modern Ram chips are either parity (ECC) or non parity (non-ECC). It is best not to mix the two types, as this can be a cause of trouble.

EMM386 error messages refer to memory problems but may not be connected to bad Ram. This may be due to free memory problems often linked to old Dos-based programs.

3. BIOS settings

Every motherboard is supplied with a range of chipset settings that are decided in the factory. A common way to access these settings is to press the F2 or delete button during the first few seconds of a boot-up.

Once inside the BIOS, great care should be taken. It is a good idea to write down on a piece of paper all the settings that appear on the screen. That way, if you change something and the computer becomes more unstable, you will know what settings to revert to.

A common BIOS error concerns the CAS latency. This refers to the Ram. Older EDO (extended data out) Ram has a CAS latency of 3. Newer SDRam has a CAS latency of 2. Setting the wrong figure can cause the Ram to lock up and freeze the computer’s display.

Microsoft Windows is better at allocating IRQ numbers than any BIOS. If possible set the IRQ numbers to Auto in the BIOS. This will allow Windows to allocate the IRQ numbers (make sure the BIOS setting for Plug and Play OS is switched to ‘yes’ to allow Windows to do this.).

4. Hard disk drives

After a few weeks, the information on a hard disk drive starts to become piecemeal or fragmented. It is a good idea to defragment the hard disk every week or so, to prevent the disk from causing a screen freeze. Go to

* Start –> Programs –> Accessories –> System Tools –> Disk Defragmenter

This will start the procedure. You will be unable to write data to the hard drive (to save it) while the disk is defragmenting, so it is a good idea to schedule the procedure for a period of inactivity using the Task Scheduler.

The Task Scheduler should be one of the small icons on the bottom right of the Windows opening page (the desktop).

Some lockups and screen freezes caused by hard disk problems can be solved by reducing the read-ahead optimization. This can be adjusted by going to

* Start –> Settings –> Control Panel –> System Icon –> Performance –> File System –> Hard Disk.

Hard disks will slow down and crash if they are too full. Do some housekeeping on your hard drive every few months and free some space on it. Open the Windows folder on the C drive and find the Temporary Internet Files folder. Deleting the contents (not the folder) can free a lot of space.

Empty the Recycle Bin every week to free more space. Hard disk drives should be scanned every week for errors or bad sectors. Go to

* Start –> Programs –> Accessories –> System Tools –> ScanDisk

Otherwise assign the Task Scheduler to perform this operation at night when the computer is not in use.

5. Fatal OE exceptions and VXD errors

Fatal OE exception errors and VXD errors are often caused by video card problems.

These can often be resolved easily by reducing the resolution of the video display. Go to

* Start –> Settings –> Control Panel –> Display –> Settings

Here you should slide the screen area bar to the left. Take a look at the color settings on the left of that window. For most desktops, high color 16-bit depth is adequate.

If the screen freezes or you experience system lockups it might be due to the video card. Make sure it does not have a hardware conflict. Go to

* Start –> Settings –> Control Panel –> System –> Device Manager

Here, select the + beside Display Adapter. A line of text describing your video card should appear. Select it (make it blue) and press properties. Then select Resources and select each line in the window. Look for a message that says No Conflicts.

If you have video card hardware conflict, you will see it here. Be careful at this point and make a note of everything you do in case you make things worse.

The way to resolve a hardware conflict is to uncheck the Use Automatic Settings box and hit the Change Settings button. You are searching for a setting that will display a No Conflicts message.

Another useful way to resolve video problems is to go to

* Start –> Settings –> Control Panel –> System –> Performance –> Graphics

Here you should move the Hardware Acceleration slider to the left. As ever, the most common cause of problems relating to graphics cards is old or faulty drivers (a driver is a small piece of software used by a computer to communicate with a device).

Look up your video card’s manufacturer on the internet and search for the most recent drivers for it.

6. Viruses

Often the first sign of a virus infection is instability. Some viruses erase the boot sector of a hard drive, making it impossible to start. This is why it is a good idea to create a Windows start-up disk. Go to

* Start –> Settings –> Control Panel –> Add/Remove Programs (Windows)

OR

* Start –> Settings –> Control Panel –> Programs and Features (VISTA)

Here, look for the Start Up Disk tab. Virus protection requires constant vigilance.

A virus scanner requires a list of virus signatures in order to be able to identify viruses. These signatures are stored in a DAT file. DAT files should be updated weekly from the website of your antivirus software manufacturer.

An excellent antivirus program is Norton AntiVirus made by Symantec ( www.symantec.com ). Another free software is Comodo Internet Security by Comodo ( www.comodo.com).

7. Printers

The action of sending a document to print creates a bigger file, often called a postscript file.

Printers have only a small amount of memory, called a buffer. This can be easily overloaded. Printing a document also uses a considerable amount of CPU power. This will also slow down the computer’s performance.

If the printer is trying to print unusual characters, these might not be recognized, and can crash the computer. Sometimes printers will not recover from a crash because of confusion in the buffer. A good way to clear the buffer is to unplug the printer for ten seconds. Booting up from a powerless state, also called a cold boot, will restore the printer’s default settings and you may be able to carry on.

8. Software

A common cause of computer crash is faulty or badly-installed software. Often the problem can be cured by uninstalling the software and then reinstalling it. Use Norton Uninstall or Uninstall Shield to remove an application from your system properly. This will also remove references to the program in the System Registry and leaves the way clear for a completely fresh copy.

The System Registry can be corrupted by old references to obsolete software that you thought was uninstalled. Use Reg Cleaner by Jouni Vuorio to clean up the System Registry and remove obsolete entries. It works on Windows 95, Windows 98, Windows 98 SE (Second Edition), Windows Millennium Edition (ME), NT4 and Windows 2000.

Read the instructions and use it carefully so you don’t do permanent damage to the Registry. If the Registry is damaged you will have to reinstall your operating system. Reg Cleaner can be obtained from www.jv16.org

Often a Windows problem can be resolved by entering Safe Mode. This can be done during start-up. When you see the message "Starting Windows" press F4. This should take you into Safe Mode.

Safe Mode loads a minimum of drivers. It allows you to find and fix problems that prevent Windows from loading properly.

Sometimes installing Windows is difficult because of unsuitable BIOS settings. If you keep getting SUWIN error messages (Windows setup) during the Windows installation, then try entering the BIOS and disabling the CPU internal cache. Try to disable the Level 2 (L2) cache if that doesn’t work.

Remember to restore all the BIOS settings back to their former settings following installation.

9. Overheating

Central processing units (CPUs) are usually equipped with fans to keep them cool. If the fan fails or if the CPU gets old it may start to overheat and generate a particular kind of error called a kernel error. This is a common problem in chips that have been overclocked to operate at higher speeds than they are supposed to.

One remedy is to get a bigger better fan and install it on top of the CPU. Specialist cooling fans/heatsinks are available from www.computernerd.com or www.coolit.com

CPU problems can often be fixed by disabling the CPU internal cache in the BIOS. This will make the machine run more slowly, but it should also be more stable.

10. Power supply problems

With all the new construction going on around the country the steady supply of electricity has become disrupted. A power surge or spike can crash a computer as easily as a power cut.

If this has become a nuisance for you then consider buying a uninterrupted power supply (UPS). This will give you a clean power supply when there is electricity, and it will give you a few minutes to perform a controlled shutdown in case of a power cut.

It is a good investment if your data are critical, because a power cut will cause any unsaved data to be lost.

Hussein Nosair

“The simplest answer is usually the correct answer”, Occam’s  razor

and

“The simplest answer is usually the most accurate answer”