The Compaq Portable II was the third product in the Compaq portable series to be introduced by Compaq Computer Corporation. Released in 1986 at a price of $ 3499, the Portable II has improved a lot compared to its predecessors. It included an 8 MHz processor, and was lighter and smaller than the Compaq Portable. There were four models of Compaq Portable II. Base Model 1 shipped a 5.25-inch diskette drive and 256 KB of RAM, while Model 2 added a 5.25-inch diskette drive and sold for $ 3599. Model 3 ships with a disk Hard 10 MB in addition to a 5.25 “floppy disk drive and 640 KB of RAM for $ 4799 at launch. Model 4 would upgrade Model 3 with a 20 MB hard drive and sold for $ 4999. Lighter than its predecessors, Model 1 weighed only 23.6 pounds compared to the 30.5-pound Compaq Portable 286. Compaq only shipped the system with a small demonstration disc, the MS-DOS 3.1 to be purchased separately. case of poorly maintained computers exploding when the non-rechargeable lithium battery on the motherboard was connected to the power supply.There were no recorded wounds.The Compaq Portable II was replaced by the Compaq Portable III in 1987.
The Compaq Portable II had room for further upgrades after the market. Compaq manufactured four memory expansion cards, 512 KB and 2048 KB ISA memory cards, and 512 KB and 1536 KB memory cards attached to the back of the motherboard. With 640 KB installed on the motherboard and both the ISA card and the expansion card, the computer could be upgraded with up to 4.2 MB of RAM. The motherboard also had room for an optional 80287 math coprocessor. There were two revisions of the motherboard, they were functionally identical although the previous version was larger. The motherboard had four ISA slots for expansion cards, two 8-bit and two 16-bit. However, the first 16-bit slot was already occupied by a CGA graphics card and one of the 8-bit slots was being used by the ATA reader controller card, leaving two available for adding cards. The keyboard is wired but uses standard PS / 2 signaling, so a DIN or PS / 2 jack can be installed to allow use of common PS / 2 keyboards (but not USB).