Friday, June 12, 2015

The Compaq Portable 486C

"The Compaq Portable 486 is a computer released by Compaq Computer Corporation in 1992.[1] Its street price upon its release with a 120 MB hard disk was 5899 USD.[6] For a model with 210 MB hard disk the price was 6899 USD, but was not available initially in May 1992.[6] Both models are equipped with an 33\66 MHz[6] Intel 80486DX2 CPU, 4-32 MB DRAM (72-pin SIMM),[3] 1.44 MB 3.5" floppy,120[5] - 1000 MB hard disk drive[3] (P-ATA),[4] Brightness control.[3] SCSI port for CD-ROM or tape.[4]" (Wikipedia)


     I got this machine from a work colleague who kept it in a timber warehouse for about 10 years or more. This beautiful machine was lying in a place with not much humidity but a lot of wood chips that got into the machine.

The first thing when I got it, I plugged the machine to a power source and PRESSED the ON button. Expecting it to blow up or expecting a miracle.

I could hear the HDD drive spin up and that was it....

Taking apart the machine

Taking this machine apart is very easy as it is based on modular assembly. It actually gives you the feeling of playing with LEGO blocks. The only problem is the screws, which are different because some screw in plastic and some in metal but same have the Torx 15 head. (T15)


You can request me the user and service manual on my email:

After taking apart all the plastics and the aluminum covers I took off the power supply and boards and drown them into isopropyl alcohol and left them to "bath" for a couple of hours. This procedure helps clean your components of dust, rust and other unwanted particles.

The plastic covers I manually cleaned them with a slightly abrasive sponge (a kitchen sponge) with some dish washing solution . Be gentle on the logos not to whip the color off them. The handle has a rubberized feeling but be careful how much pressure you apply as it can damage the rubber layer.

Upgrades and Fix

It had 4 MB EDO ram and I had increased that to 20MB.

I put silicon based grease on the vents bearing.

Used a lot of contact cleaner for every slot and cables.

Replaced the DALLAS Bios Battery

Fixed the Display as it was a fading white with no contrast over black you could barely read the text of it. You can fix this by tweaking with a wooden or plastic Philips screwdriver like tool. Because the screen gets DE calibrated over the years.

Booting up the 486

After all this fixes I started the machine. It counted only 2 MB of RAM and I got a few ERROR messages that I couldn`t get through even if I pressed the F1 Key.

In order for the machine to recognize the whole amount of memory you have to use some kind of Reference Diskette that IBM PS2 used in the 80`s and 90`s. It is called a System Configuration Utility Diskette from COMPAQ... I had found it after days of search over the internet. I can provide that as well over email as it has only 520kbs. This is like a BIOS setup but the fields you can actually change are very limited as it requests some kind of service code to change the port configuration or other IDE transfer modes etc.

The machine has now an Intel 486 DX2 CPU running at 66 MHZ with 20 MB of RAM, a fully operational 2.5 Diskette unit and a 120 MB Hard Drive. I could also find a corrupted install of Windows 3.1 and a Windows 95 installation KIT and SUPAPLEX!

I will FORMAT this drive and install a fresh copy of Windows 95 version A, the 16 (1.44) diskettes version but I need to format my 1.44 diskettes to 2 MB diskettes using a early version of WIN-IMAGE that works on XP desktops.

Below you can see the BEFORE and AFTER pictures. 

More photos:

COMPAQ 486C Portable


  1. Hi Bogdan, nice post you placed here! Thank you!

    Can you help me with the utility software for memory upgrade? My e-mail:

    Thanks very much in advance, rgrds Thomas

  2. Hi Thomas, I just emailed you the utility software, all you have to do is copy paste that on a disk and after the system counts the memory press the F10 I remember :) have fun!

  3. Hello ! I hope you will see my message
    I also need the utility software =/
    Could you send it to me too ? email :
    By the way, impressive work of yours !!!