Although the 80286 was available for some time before IBM's introduction of the
PC AT, other companies including Compaq believed they had to wait for IBM to set the standard before releasing in 1985 their own AT clones, such as the Deskpro 286. Although the PC AT and
PC DOS did not fully use the 80286's power, the repeated failures of companies that attempted to significantly vary from IBM's designs discouraged others from trying. By mid-1986 IBM had not yet released a 80386-based computer.
John C. Dvorak surmised that IBM was unwilling to use the CPU as doing so might cannibalize profits of its
midrange computer offerings, including the
System/36 and
System/38. In January 1986 Compaq engineer Hugh Barnes told cofounder and CEO
Rod Canion that, according to Intel engineers, IBM was not yet interested in using 80386. Hoping to become the PC technology leader, Canion contacted Intel president
Andy Grove and offered to develop computer hardware using the processor. The Deskpro 386 was developed in large part by Gary Stimac, Compaq's vice president of engineering and the company's fifth employee hired. Stimac led a team of people who eventually grew to 250 in the middle of 1986. Development of the Deskpro 386 was a close collaboration between Compaq, Intel, and
Microsoft, who each signed a three-way
non-disclosure agreement. The Deskpro 386 project officially commenced in March 1985, after Intel shared Compaq the first
block diagram for the 80386 processor architecture. Stimac described this diagram as a listing of the 386's new and upgraded features, as well as a schedule of milestones for its development and eventual production runs. In June 1985, Intel delivered to Compaq detailed specifications of the 386, after which Compaq laid out a block diagram of future product lines to integrate the processor. The Deskpro 386 was the first implementation of the 80386 processor in a computer system for sale to the public. Compaq was aware that by introducing the Deskpro 386 first, a future IBM product might be incompatible with and obsolete it. Canion had said as early as December 1982, during a
Boston Computer Society presentation, that IBM could not revert to proprietary computers without hurting itself. With Deskpro 386, the company again predicted that IBM would not greatly change the PC architecture as doing so would also orphan millions of real IBM PCs.
PC wrote "Compaq's conclusion: IBM's DOS standard is now bigger than IBM". Although expecting IBM to become the leader in 386-based systems,
Computerworld wrote that when the company did ship them "it must follow the installed base [and] the de facto industry standard for the 80386 market, a standard that no longer bears the name IBM". Microsoft was brought on board as a consultant for potential software compatibility issues with the plethora of
MS-DOS-based software on the market. As well, Compaq asked Microsoft what other
operating systems they could provide that had better 32-bit support for the 386. By the time of the Deskpro's release, the most advanced operating system that Microsoft offered was
Xenix System V/286, which Compaq offered as an optional pack-in for selecting buyers. A 32-bit version for the 386 was promised in the first quarter of 1987. Early prototypes of the Deskpro 386 were designed around the 12-MHz clock speed of the earliest production batches of the 80386 and so featured a 6-MHz bus clock. By the time the Deskpro 386 came out, yields of 16-MHz 386's had reached acceptable numbers, and so the bus clock was upgraded to 8 MHz. Regarding RAM, four different paths were taken by Stimac's team to determine the best memory configuration for both performance and cost. A
static-column DRAM design was chosen as the winner, against pure
page mode DRAM,
traditional asynchronous DRAM, and DRAM backed with
cache. On the
mass storage front, the use of
SCSI hard drives was considered early on but abandoned due to a performance penalty incurred with SCSI
drive controllers over the ISA bus. They found a vendor of ESDI drives that were able to put the controller hardware onto the drive itself, leading to acceptable performance. ==Release==