Compaq Portable III


Wiki – setup disks




The computer will not access HDD when the CMOS battery is discharged or absent. There are two versions of the batteries possible:

  • Integrated inside Dallas DS1287 real time clock controller chip. It is easy to replace the integrated battery with an external one, following these instructions. Please mind that my computer is missing the back cover, so maybe the battery needs to be positioned differently, but the idea is basically the same.
  • Separately soldered to the board, with MC146818 chip instead of DS1287 – this version will have additional resistors, diodes and oscillator soldered near the chip and the battery. These components are missing in the Dallas version where some zero-ohm links are soldered instead.

Video Board

Floppy Disk Drive

Canon MD 5501

Hard Disk Drive

Conner CP3041

Power Supply


Panasonic MD400F640PD5 – gas plasma display.


This is not the original keyboard coming with Portable III, but one taken from Compaq Portable 386. The keyboard seems to be compatible, also physically fits the cover perfectly.

Compaq Portable keyboards had cords in which the plastic cable coating broke easily with time and fell off leaving the bare cables visible. A vintage keyboard extender may be used as a replacement.



Signal at pin 2 of the LCD screen 4-pin power connector