This page covers only the proprietary BIOS developed by Compaq. Other types of BIOSes used by Compaq computers are not covered in this page.
Compaq was one of the earliest developers of BIOS, creating the first instance of its own BIOS firmware in 1983 for the Compaq Portable PC. This was less than a year before the release of PhoenixBIOS, the first commercially available BIOS firmware developed by Phoenix Technologies. Despite this, alongside the availability of other commercial solutions such as AMIBIOS from American Megatrends (now AMI Inc.) and AwardBIOS from Award Software, Compaq continued to develop its own BIOS for many years until it was acquired by Hewlett-Packard (HP) in 2002. After the acquisition, HP continued to develop and use this BIOS for a few more years (specifically for the HP-Compaq line of computers), until it was discontinued in favor of commercial BIOS solutions and, shortly thereafter, UEFI-based solutions (mostly AMI Aptio).
Development timeline
Below is a list of significant changes made to this BIOS during its development. As Compaq never used version numbers to identify their BIOS core versions (they were only used for ROM releases for each computer model), these changes are listed by the approximate year they first appeared in known/tested ROMs. Therefore, inaccuracies may be present in the information contained in this list.
Compaq Computer Corporation era
Pre-1983
The Compaq Portable, which would be the first computer to use this BIOS, was announced in November 1982. Although not much is known about the development of the computer, its BIOS was likely already being developed by this time.
To provide full compatibility with IBM PC software, Compaq needed a BIOS that essentially functioned the same as the IBM BIOS. However, despite its technical documentation being publicly available, the IBM BIOS -along with its code- was copyrighted. Therefore, to avoid legal trouble, they had to develop the BIOS by using a clean room design. This worked well as Compaq was able to develop a BIOS that was fully compatible with IBM PC software yet did not infringe IBM's copyright.
1983
The Compaq Portable was released in March 1983; quickly becoming a commercial success due to its affordability, portability and full IBM PC compatibility. With this, the initial version of Compaq BIOS also became available.
Unlike later versions, the initial version of Compaq BIOS does not have a visible memory test as it initializes video after the test (instead of before like on later versions). Therefore, nothing is displayed on the screen for the duration of the test.
During video initialization, a screen with garbled color blocks and text is displayed for a brief moment. After the initialization, if an operating system disk is detected, the system starts booting from the disk. If no disk is detected, a "Diskette error" message is displayed instead.
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The garbled video initialization screen
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The "Diskette error" message
1984
Compaq Deskpro, a desktop computer based on the Intel 8086 processor, was released in June 1984. This computer's BIOS is visually almost identical to that of the Compaq Portable, but without the garbled video initialization screen. Therefore, no video is output until the boot process.
This BIOS version also POSTs significantly faster than the older version on the Compaq Portable, even with an equally clocked processor.
1985
With the release of the Compaq Deskpro 286 and Portable 286, the Compaq BIOS was significantly revised, adding a visually visible memory test and POST error messages.