The Compaq Portable is an early portable computer that was one of the first IBM PC compatible systems. It was the first product of Compaq Computer Corporation, followed by others in the Compaq Portable series and later the Compaq Deskpro series.
It was not just a computer with an Intel 8088 processor running Microsoft DOS as its operating system, but a full-fledged clone of IBM thanks to the reverse-engineered BIOS. As well, this was one of the first portable IBM PC compatible clones.
It became available two years after the similar but CP/M based Osborne 1 and Kaypro II. The MPC 1600 Multi Personal Computer from Columbia Data Products was released in June 1982. Other towables were the MS-DOS and 8088 based, but not fully compatible with IBM PC software, Dynalogic Hyperion, Eagle Computer's Eagle 1600 series and the Corona personal computer. The latter two companies were threatened by IBM for BIOS copyright infringement, and settled out of court and agreed to re-implement their BIOS.
Unlike Compaq, many of these companies had previously released computers based on Zilog's Z80 and Digital Research's CP/M operating system. Like Compaq, they recognized the reproducibility of the IBM PC's out-of-the-box components and saw that Microsoft retained the right to license MS-DOS to other companies. Only Compaq was able to take full advantage of this by aiming for full compatibility with IBM PC and PC DOS software, while reverse engineering the BIOS to avoid legal claims over copyright.
Compaq's efforts were possible because IBM had primarily used pre-assembled PC components and published full technical documentation for them, and Microsoft retained the right to license MS-DOS to other computer manufacturers. The only difficulty was the BIOS, as it contained IBM's copyrighted code. Compaq solved this problem by producing a functional copy that performed all the documented functions of the IBM PC BIOS, but developed completely on its own.
While many other companies soon began selling PC-compatible PCs, few matched Compaq's achievement of essentially full software compatibility with the IBM PC (usually reaching up to 95% compatibility) until Phoenix Technologies and others launched similar reverse-engineered BIOSes. the computer started to sell.
The first Portables used Compaq DOS 1.10, essentially identical to PC DOS 1.10, except it had a standalone BASIC that didn't require the IBM PC's ROM cartridge BASIC, but this was replaced by DOS 2.00 within a few months. which added hard drive support and other advanced features.