Solutions/explanations for common PC problems

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Not all PC problems are caused by failed hardware. Check here for some common problems and their non-hardware fixes before buying new memory, floppy drives or other hardware. HINT!! Use CTRL+F (find function) to locate keywords you are looking for on this page..

  1. DOS only sees 16MB of my 24/32MB of installed memory.
  2. My PS/2 or Serial mouse won't work on an adaptor cable.
  3. I get "Invalid Drive Specification" message when I try to access my C: drive.
  4. My system/motherboard doesn't recognize 8MB SIMM's.
  5. What are the VR, VRE, VRM voltage ranges I need to select for my Pentium CPU chip?
  6. WIN95 Explorer reports 650MB disk space used and my backup utility reports 580MB used?
  7. My printer feeds a single page with one or two garbage characters when I start Win95.
  8. My system runs fine but my COM ports or Modem gives errors or won't operate at all.
  9. Can I tell if I have a virus on my machine without a virus detection program?
  10. Where can I find setup diskettes for the old Hewlett Packard 286/386 ES/QS/RS "legacy" PC's?
  11. How can I copy Win95 from my old drive to my new (larger) hard drive without reinstalling Win95?
  12. How do I access the CMOS (BIOS) of my old 286 AT system?
  13. My floppy drive LED(s) stay on all the time after power up and I can't access the drives.
  14. When I do a DIR command the floppy drive only reports the files of the first diskette that was read.
  15. I want to reverse the A:, B: order of my diskette drives (with no CMOS changes avail) how do I do this?
  16. What is BIOS shadowing?
  17. Epson 500 inkjet. The ink out lights stay on after replacing cartridge (Power ON reset sequence)
  18. I get constant keyboard errors or no keyboard found on power up but the keyboard works on another system
  19. Do I need to spend the money for a IEEE1284 compliant cable on my new system or printer?
  20. What is the difference between the standard parallel port and the "enhanced" IEEE1284 parallel port.
  21. How can I tell if my printer cable is 1284 compliant or not?
  22. On powering up my PC, my hard drive(s) are not detected. When I do a soft boot (reset) they are detected fine.
  23. I can read some CD's on my CD drive and some will not read at all. I was able to read them OK before and they read OK on another system.
  24. I have Netscape Communicator 4.0. How can I stop the AOL instant message applet from starting all the time?. I don't use AOL.
  25. Can I use a Pentium MMX chip on my MB? What is the difference? Will my BIOS support it?

  1. Why does my system see all my memory above 16MB on POST but DOS only sees 16MB.

Answer: When installing more than 16MB of memory, BIOS relocation must be disabled.
BIOS relocation copies the video BIOS (C0000-C7FFF) and the system ROM BIOS (F0000-FFFFF) into RAM.
The motherboard (BIOS?) adds 15MB to these addresses (F00000) to be able to differentiate between the ROM and RAM.

Enabling the relocation feature causes the memory above 16MB to become non-contiguous and therefore inaccessible.

For DOS to size and utilize the memory above 16MB you MUST disable all BIOS and video ram relocation
and/or caching settings in your CMOS setup. It may slow the system down somewhat but this is a throwback
to the 286 memory limitation (24 bits) for 16MB of addressable memory.

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2. My PS2 mouse won't work on my serial port with an adapter cable.
. My serial mouse won't work on my PS2 port with an adapter cable.

Answer: PS/2 mice and serial mice are two different devices. The ID bits returned from the
mouse to the mouse detection S/W routine are different to differentiate the two devices.
A mouse labeled PS2 port mouse will ONLY work on a PS2 port.
A mouse labeled serial mouse will only work on a serial port.
Mice labeled PS2/Serial compatible (or a derivative thereof) can be adapted to work
on either serial or mouse ports with the proper adapter cables(s).
If your mouse has a single designator printed on the label on the bottom of the mouse
then it is a single mode mouse.

Click here for a detailed explanation of serial and PS2 mouse interface and protocols.

Another twist on this problem are mice that have a slide switch on the bottom that reads MS or PC.
MS is for Mouse Systems (Not Microsoft) and will not work without a Mouse Systems driver.
If you have this switch on your mouse, set it to PC for standard mouse drivers.

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3. Common causes of "Invalid drive specification" messages.

Answer: There are several sets of circumstances that can return this status.

A. If the drive has not been partitioned (with FDISK) this message will be reported.

B. If the drive parameters (Cyl, Hd, Sec) set in CMOS DON'T match those of the drive
this message will be returned indicating that the drive geometry read from the drive
doesn't match what is entered in CMOS.

C. General hardware failure on the disk sub-system where the drive geometry cannot be read
(causing the mismatch described in B). This could be a bad cable, misplaced cable
(off by a pin or row) no DC power to the disk, bad disk PCB, incorrect jumpering on disk PCB.

Any matter of problems that can cause the disk to be unreadable can return this error message.

NOTE!! On initial HDD install/upgrade I'd do a physical check on all the obvious things like
cable placement, power connectors, listen to hear the disk seeking during it's POST test on pwr up.
If this error occurs after the disk has been operating normally it is indicative of a failure of some type.

This may be a hardware failure, or partition data may have been corrupted. This is NOT a good message
to get from a working drive.

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4. My motherboard/system doesn't recognize 8MB SIMM's when I install them.

Answer: 2MB/8MB and 32MB SIMM's are what are know as "dual density" SIMM's. They are really two
1MB/4MB/16MB banks mounted on one SIMM PCB. In order to utilize "dual density" SIMM's the
memory controller MUST support dual RAS(Row Address Select) and dual CAS(Column Address Select)
strobing functions. Many memory controllers DO not support dual RAS/CAS strobing. In this case the SIMM
MAY be recognized as 4MB or not recognized at all.

If your MB manual doesn't list 2MB/8MB/32MB memory SIMM's in the memory matrix chart
in the manual then it probably doesn't support "dual density" SIMM's.
General rule of thumb is that "dual density" SIMM's will have components mounted on both sides
of the SIMM PCB.

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5. What are the ratings of the VR, VRE, VRM voltage jumpers select on my MB?

Answer: The Intel Pentium processors, AMD K5's and the Cyrix 6x86's run at varying core voltages for optimum performance and lower heat dissipation.

General rule of thumb is the higher the clock speed the lower the core voltage. It is IMPORTANT that the correct CPU core voltage be selected to avoid damaging the CPU. The different voltage designators are as follows:

STD = 3.135V ~ 3.6V

VR = 3.3V ~ 3.465V

VRE = 3.4V ~ 3.6V

VRM = Voltage Regulator Module/Header (Socket 7)

Follow this link for more detailed information from ECS's Web site.

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6. WIN 95 Explorer reports 650MB of disk space used and my backup utility reports 520MB used?

Answer: If you partition your hard drive (>540MB) as one large partition then DOS/WIN sets a cluster size for read/write operations of 64 sectors or 32KB. This means that the SMALLEST data record written to the drive is 32KB in size. If your create a 5K file it will write that file within a 32KB cluster on the disk and reserve the rest of the 32KB for expansion of that file. Explorer reports disk usage in clusters used rather than in true file size. If you have four 5KB files on your drive they will occupy/reserve 128KB of space on your disk even though they are only occupying 20KB of actual disk space. Most backup utilities only have to save the data to tape and report the file size in actual calculated bytes and not in cluster size. This mathematical difference is what causes the file size discrepancy.

To see a graphical representation of your drive in WIN95 do the following:

Click START ==>select Explorer ==>select C: ==>right click when C drive is highlighted ==> go to properties and right click again

Or click My Computer ICON==>right click on C: drive ICON==>right click on properties

A pie chart will display showing the amount of disk space currently used/reserved on this drive.

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7. My printer feeds a single page with one or two garbage characters when I start Win95.

Answer: This problem can occur with laser, Inkjet or matrix printers. It is caused by a file named DRVWPPQT.VXD, This file is part of Seagate's (Arcada) parallel port tape backup support. If you are using or have loaded the Seagate (Arcada) tape backup software and do not have a tape drive attached to the parallel port then simply delete the file with Explorer. Use the FIND command from the START menu to locate the file or go to C:\WINDOWS\SYSTEM\IOSUBSYS and delete the file. If you happen to have a parallel port tape backup unit, it is anomaly that you will have to live with as the problem occurs when the tape driver is "talking" to the parallel port during system initialization.

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8. My system runs fine but I cannot get my COM ports, internal modem or communications cards to work.

Answer: The +12V and -12V from the DC power supply are ONLY used on the COM ports, modems and communications cards to meet the EIA specification for line voltages. The older 5.25" full height drives used to use +12V for the spindle motor but today's 3.5" drives now use 5V for the spindle motor and logic. Because of this, if the +/- 12V in the power supply is bad (low/high, missing, ripple or sawtooth) then the COM ports, modems and communications cards (muxes, attachmate's etc) will fail to operate correctly. The failure symptoms will vary but everything else in the system will work fine except the COM ports and modems. You can check the DC power with meters or scopes but in today's commodity PC world it might be cheaper and quicker to plug a new P/S into the MB and see if the problem goes away.

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9. Can I tell if I have a virus on my machine without a virus detection program?

There are several "low tech" ways of checking for viruses without having a virus detection program. They are not fool proof but can be a starting point to confirm virus suspicions.

A. Go to a DOS window and run CHKDSK. The total bytes of memory reported should read 655,360 (640 X 1024). If it reports any value less than 655,360 there is a good chance that there is a memory resident virus in your system.

B. WIN95

Open DEVICE MANAGER and look at the hard disk controllers.

If either or both ICONS have a yellow exclamation point over them it is a telltale sign of a VIRUS. This will be displayed for IDE/MFM/ESDI controllers but NOT for SCSI controllers.

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10. Where can I find setup diskettes for the old Hewlett Packard 286/386 ES/QS/RS "legacy" PC's?

Answer: Go to ftp.netserver.hp.com and login as:

user: anonymous

passswd: your_email_address

go to the obsolete directory

Voila!!! there they are in EXE format and zip format.

To FTP these files directly from your Netscape browser CLICK HERE .

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11. How can I copy Win95 from my old drive to my new (larger) hard drive without reinstalling Win95?

Answer: You will need your hard drive CMOS and jumper settings (both drives) and a Win95 Starter diskette.
Prior to moving any data around install your new drive as the D: drive following steps 1-6 below.

  1. Configure OLD drive as master drive in a 2 drive system. (See your documentation for jumper settings)
  2. Configure NEW drive as 2nd drive in a dual drive system. (See your documentation for jumper settings.)
  3. Power up system, enter SETUP and configure CMOS settings for each drive.
  4. Boot from your Win95 starter diskette.
  5. Load FDISK to initialize the D: drive (1). Say NO to question about using the whole partition and making it active. Select the primary partition and set it to the size you want and any extended partitions (your decision).
  6. Reboot the starter diskette and run the DOS> FORMAT D: /S command to put the system files on the D: drive.

Moving data using the XCOPY command:

Moving data using the WIN95 EXPLORER:

Putting new drive in as C: drive.

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12. How do I access the CMOS (BIOS) on my old IBM 286 AT system

Answer: A SETUP diskette is required to access the CMOS of the IBM AT series systems..

Get a copy of the IBM diskette at the following URL. The technology was common for the early 286 systems and this CMOS SETUP diskette will work on other 286 systems of similar technology.

ftp://ftp.pc.ibm.com/pub/pccbbs/refdisks/

PS/2 reference diskettes from ComputerCrafts PS/2 page.

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13. My Floppy drive LED stays on all the time on power up and I can't access the drive.

Answer: This symptom often occurs after working on a system or after installing a new motherboard. It is caused by the floppy drive signal cable being reversed on the drive or on the MB/controller connector.

On a single floppy drive system just reverse the cable at the motherboard/controller end to resolve the problem.

In a dual floppy system if one drive works and one drive fails reverse the connector on the rear of the failing drive. If both drives fail, reverse the cable at the motherboard/controller end.

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14. When I do a DIR command the floppy drive only reports the files of the first diskette that was read.

Answer: There is a floppy drive function called Disk Change Interrupt which notifies the system with an interrupt from the floppy drive whenever a disk is inserted in the drive. If the system does not see this interrupt it asumes there was no new disk inserted and displays the FAT from the first floppy read. There is a jumper on the drive to enable/disable this interrupt that could cause this problem. Check to see that the Disk Change Interrupt jumper is set to enabled.

Another possibility is the signal cable itself. The Disk Change Interrupt line is pin 34 (last one) on the cable and if the cable is cocked on the signal connector of the drive, you could miss this interrupt and still have proper operation of the floppy for read write purposes. Reseat the signal cable on the rear of the floppy drive for this error.

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15. I want to reverse the A:, B: order of my diskette drives (with no CMOS changes avail) how do I do this?

Answer: If you look at your FDD cable there are two sets of 34 pin connectors (Universal FDD cables have two sets of connectors, 34 pin edge and 34 pin Dual In Line (DIL) at each position on the cable so that you can install 3.5" or 5.25" drives as either drive letter.) . There are 5 wires twisted between the two sets of connectors. Typically both drives are jumpered for unit #1 on their R/W interface PCB.

The twist in the cable reverses the device address lines so that the drive AFTER the twist (on the end connector) becomes UNIT#0, (drive A) and the drive on the connector without the twist is UNIT#1. (drive B) To reverse the drive letters (without the new CMOS drive change capability) simply put the current B: drive on the last cable connector (after the twist) and put the current A: drive on the connector with no twist.

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16. What is BIOS shadowing?

Answer: Many I/O controllers have their own BIOS (Basic Input Output System) chip which contains the necessary code to invoke the various functions of the controller. The most common types of controllers that have their own BIOS are video cards and disk controller cards. Whenevr a function needs to be invoked the BIOS is read into memory in order to execute the code. This I/O function usually happens at I/O bus speeds which is 16MB's per second for ISA bus cards. When you enable "BIOS shadowing" or caching, the contents of the controller BIOS chip is read and stored in main memory and whenever an I/O operation requires reading the BIOS, it is read from memory at 70-80ns speed instead of the 16MB/sec I/O speed.

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17. The ink out light stays on all the time on my Epson SC500 even after changing the cartridge(s).

Answer: This occasionally happens and I have not been able to determine the actual cause but there is a solution.

Hold down ALL three buttons on the front panel and then power the printer on, holding the buttons down for 10 seconds. Release the buttons and press the load/eject button one time. The light(s) should go out.

Link to Epson's SC 500 FAQ page.

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18. I get constant keyboard errors or no keyboard found on power up but the keyboard works on another system.

Answer: The +5V source for the keyboard is FUSED on the MB by a small (1/2A or 3/4A) ceramic fuse. If this fuse blows, there is no +5V for the keyboard (or PS/2 mouse) and error messages will be displayed on power up. A visual indicator is that the keyboard LED's do not light up on power up.

The fuse will be located very close to the keyboard connector on the MB and is about 3/4" long, 1/8" in diameter and is grey or off white on color. All you need to do is solder a new 1/2A fuse across this one. There is no need to remove it from the MB as it is blown anyway. DO NOT bridge this fuse with a piece of wire unless you want to chance destroying your MB or P/S on the next shorting of this 5V. These fuses can be found at a local Radio Shack.

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19. Do I need to spend the money for a IEEE1284 compliant cable on my new system or printer?

Answer: YES. If your printer is IEEE1284 compliant and your parallel port is 1284 capable then you should use a 1284 compliant cable to get proper results. Various malfunctions and/or errors can result. Numerous system to printer anomolies have been resolved by using a 1284 compliant cable..

In the case of my Epson 500 color inkjet, it does not show the ink levels in the status monitor screen with the standard cable, as this is data returned from the printer to the driver after each print job. The returned data is not read correctly with a standard printer cable. If your parallel port is not IEEE 1284 capable then there is no reason buy a 1284 compliant cable for your printer.

The Belkin IEEE1284 cable is $20 at Walmart and is the same cable sold at CompUSA for $38. (Check the Belkin SKU on the package) CostCo also sells a 1284 cable for $9.95. (I don't know the SKU)

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20. What is the difference between the standard parallel port and the "enhanced" IEEE1284 parallel port.

Answer: The principal difference is that the standard parallel port xfers data at about 150Kbytes per second and the IEEE1284 port xfers data at about 2Mbytes per second (about 13 times as fast). Due to this speed difference the IEEE1284 cable is built to higher standards. Each pair of wires in the 1284 cable is individually shielded to reduce crosstalk in the cable. 2Mbyte/sec signals can be distorted by the capacitance in a standard cable where they cannot be read by the receiving device.

1284 also adds the ECP mode and the EPP modes to the port. These modes make the use of bi-directional devices like tapes and disks possible on the parallel port.

See Warp Nine's information page for detailed information on the 1284 parallel port standard.

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21. How can I tell if my printer cable is 1284 compliant or not?

Anzwer: 1284 compliant cables have 1284 or 1284 compliant stenciled on the outside jacket of the cable. Just look along the length of the cable for the number 1284 stenciled on it.

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22. On powering up my PC, my hard drive(s) are not detected. When I do a soft boot (reset) they are detected fine.

Answer: This problem could occur after a MB change, a HDD add or a BIOS update.

The problem is caused by the fact that the newer (high speed) processors finish the POST (Power on Self Test) very quickly and the newer (more complex) hard drives take longer to complete their POST . This combination of timing issues causes the drive NOT to be ready when the BIOS looks for it after completing it's POST and therefore reports no drives attached. After resetting the systems the drives are detected because they do not POST on a system reset and are ready when the BIOS looks for them.

There are two possible solutions to this problem.

  1. In some of the newer BIOS's there may be a BOOT DELAY parameter for the HDD's. This delay is the amount of time to wait for the disk to come ready. Generally setting the BOOT DELAY for 5 seconds will resolve this error.
  2. If your BIOS does not have a BOOT DELAY parameter check to se if it will AUTO DETECT your HDD's on boot. If so select AUTO DETECT for the HDD's. This will force the BIOS to wait for the drive to come ready in order to read the drive parameters from the drive.

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23. I can read some CD's on my CD drive and some will not read at all. I was able to read them OK before and they read OK on another system.

Answer: This problem has been resolved by replacing the CRTDLL.DLL file in the C:\windows\system directory. Just why some CD's read and some don't is unknown. Perhaps a multi-session recording issue?

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24. I have Netscape Communicator 4.0. How can I stop the AOL instant message applet from starting all the time?. I don't use AOL.

Answer: Open the Instant Message option from the Netscape toolbar. Click on the SETUP Icon on the AIM dialog window.

Select the MISC tab. Uncheck the box that says, Start AIM when Windows starts. Your problem is resolved.

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25. Can I use a Pentium MMX chip on my MB? What is the difference? Will my BIOS support it?

Answer: The Pentium MMX chip is a socket 7 pin compatible chip that has a "dual rail" voltage configuration. That is the CPU uses a 2.8V core voltage and uses 3.3V for the I/O like other Pentium CPU's. (The std Pentiums were 3.3V chips). The additional 57 MMX instructions are internal to the CPU and transparent to any BIOS's or MB considerations. If your MB states P55C compatibility in the specifications it will (should) support the dual voiltage MMX chip.

BIOS upgrades MAY be required for some MB's to identify the MMX chip properly but this is a cosmetic issue. It seems that Intel documented the voltage requirements to designers before the MMX CPUID specs were released. If the MB supports dual voltage the CPU will function properly.

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