The Compaq Portable 386 is a computer released by

Compaq Computer Corporation Compaq Computer Corporation (sometimes abbreviated to CQ prior to a 2007 rebranding) was an American information technology company founded in 1982 that developed, sold, and supported computers and related products and services. Compaq produced ...

in 1987. It was equipped with a

Intel 80386 The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistorsCPU,

RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...

, ROM,

floppy A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined wi ...

hard disk drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...

, priced at respectively, and a gas-plasma display. Early versions of the Compaq Portable 386 were sold with the Compaq Portable III case and badges. A differing screen bezel stating "386/20" was the only externally visible change.

Network General NetScout Systems, Inc. (stylized as NETSCOUT) is a provider of application performance management and network performance management products located in Westford, Massachusetts. In July 2015, NetScout acquired the communications business of Dana ...

resold a customized version of the Compaq Portable 386 as the " Sniffer" Network Analyzer.

Technical data in detail

CPU and FPU

The Portable 386 got its name due to the socketed Intel 386DX CPU with 20MHz. There is also an additional socket for a 20MHz 387 FPU option, which was not included in the basic configuration of the Portable. Since the whole system bus runs with CPU frequency, there is no way to improve the CPU performance by installing a 386DX CPU with more than 20MHz other than the rare ''Cyrix 486DRx2 20/40'' which has a multiplicator of 2 for the frequency while being still pinout compatible with the 386 socket.

Memory

The mainboard can take up to four proprietary 512KB SIMMs which were called SC-RAM in the Portable manual. Additionally, there was an expansion slot inside the Portable which allowed to expand the memory by another 8MB alongside the 2MB on the mainboard by: Installing the so-called ''32bit Memory-/Modem board expansion'' offers a socket for another expansion card which has 4MB (8×512 KB 80 ns) of memory and another expansion socket installed on which the user can install a 3rd expansion card with another 4MB (again 8×512 KB 80 ns) of RAM. These RAM expansion cards were available through Compaq or third party manufacturers, such as

Kingston Technology Kingston Technology Corporation is an American multinational computer technology corporation that develops, manufactures, sells and supports flash memory products, other computer-related memory products, as well as the HyperX gaming division ...

Graphics card

The graphics card can be configured between CGA and

MDA MDA, mda, or ''variation'', may refer to: Places * Moldova, a country in Europe with the ISO 3166-1 country code MDA Politics * Meghalaya Democratic Alliance (2018), ruling coalition government in the Indian State of Meghalaya led by National Pe ...

emulation mode whereas the CGA mode is mandatory for using Microsoft Windows' Compaq Plasma Driver and graphic capabilities in general. The internal CGA graphics card is able to display a resolution up to 640x400 pixels with a color depth of 2 bits (monochrome), which has been first seen in the

AT&T 6300 The Olivetti M24 is a computer that was sold by Olivetti in 1983 using the Intel 8086 CPU. The system was sold in the United States under its original name by Docutel/Olivetti of Dallas. AT&T and Xerox bought rights to rebadge the system as t ...

built by Olivetti, surpassing the original IBM standard by 200 pixels in height while remaining fully CGA compatible elsewhere. The internal gas plasma display is able to display 640x400 pixels with up to 16 shades of gray and is connected to the graphics card via a proprietary connector. Users can install a better graphics card via the ''Compaq Expansion Unit'' (more on it later), but cannot use it with the internal display for sure.

Hard disk

The Portable offers two

drive bays A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed. Over the years since the introduction of the IBM PC, it and its compatibles have had many form f ...

for 5.25" half-height drives where one is reserved for the hard disk and the other one for the internal floppy disk drive. Compaq originally offered a 40MB and 100MB hard disk option. Quite common back in the days, the BIOS of the Compaq only offers to select preconfigured hard disk configurations like Type 17 for 40MB or 42 for 504MB. There is no detailed information about the underlying CHS configuration of these types available. The device suffers from the wide-spread CHS barrier, not allowing hard disk drives greater than 504MB.

Floppy Disk Drive

In its basic configuration, Compaq offered only a single 5.25" 1.2MB floppy disk drive aside of the 40MB hard disk drive, but there was also a cheaper option for a secondary 5.25" 360KB floppy disk drive instead of the hard disk. Giving the fact that the Portable uses a standard floppy drive connector and has built-in support in the BIOS, one can easily replace the 5.25" with a 3.5" 1.44MB drive.

External expansion options

In order to better position the Portable as a professional office computer, Compaq also offered multiple external expansion which can be installed on the back of the Portable while the device is turned off. ; Compaq Expansion Unit : As mentioned before, there is an expansion unit available which extends the Portable by two full-size 16bit ISA slots. Compaq advertised ISA cards like the ''COMPAQ-VG-Controller card'' to be used with the expansion unit. This card allows to display (for back-then standards) groundbreaking 720×400 pixels for text and 640×480 pixels for graphics with up to 256 colors (palette of 256.000 colors) at the same time on an external ''Compaq VG display''. ; Compaq Expansion Unit with a 40MB tape drive : There was also an expansion unit for a 40MB tape drive offered, which looks identical to the ISA expansion unit from outside, except for offering only a slot for the tape drive.

Internal expansion options

Compaq offered multiple expansion cards for the Portable 386, which can be installed inside the main housing. Similar to the external expansions, these internal expansion cards cannot be exchanged while the device is turned on. ; 32bit Memory-/Modem board expansion (carrier board) : This expansion card is mandatory for installing additional expansion cards. It is not only a carrier board for other expansions, but also offers a 2400 baud modem. ; 1-2MB memory expansion : The 1-2MB memory expansion must be installed on the 32bit carrier board and comes with 1MB of RAM preinstalled and offers two more SC-RAM slots for 1MB SC-RAM memory modules each. It cannot be used together with the other 4MB memory expansions due to a missing connector. ; 4MB memory expansion : This expansion also requires the carrier board to be installed and offers 4MB of preinstalled memory. ; 4MB additional memory expansion : This extension board for the 4MB memory expansion card just offers another 4MB of preinstalled memory and is installed on top of the 4MB memory expansion. It maxes out the supported memory of 10MB. ; Asynchronous connection extension : This expansion card offers only an RS232 connector. It cannot be used together with the carrier board. ; 1200 resp. 2400 Baud Modem : This expansion was only available in form of a set including a 1200 or 2400 baud Hayes-compatible modem, an own carrier board, a housing cover with a modem connector and a telephone cable for the American and Canadian markets.

BIOS

The BIOS setup utility is not preinstalled in an EPROM chip, but comes on a single floppy disk. If a user is no longer owning such a disk, it can be still easily found at archive.org/details/CompaqPortableDiagnosticDisk * 3.5″ 720KB version: SP0308.EXE / SP0308.ZIP or * 5.25″ 360KB version: SP0316.EXE / SP0316.ZIP

Software

Compaq bundled Compaq-DOS in version 3.31 with the Portable 386, a variant of MS-DOS 3.2 which already offered support for FAT16 and hard disk partitions with more than 32MB. A Windows 2.01 OEM version was also available which makes use of the 386 memory management. There was also a User Programs disk bundled with the Portable which offers tools for memory management and adapting the CPU speed (between 6, 8 and 20MHz): * ''ADAPT.COM'' (Advanced Display Attribute Programming Tool) a TSR application to configure the CGA/MDA charsets on the fly. * ''CACHE.EXE'' (Compaq Disk Cache) works similar to the commonly known

SmartDrive SmartDrive (or SMARTDRV) is a disk caching program shipped with MS-DOS versions 4.01 through 6.22 and Windows 3.0 through Windows 3.11. It improves data transfer rates by storing frequently accessed data in random-access memory (RAM). Early ...

in alter MS-DOS versions * ''CEMM.EXE'' (386 CPU) / CEMMP.EXE (286 CPU),''Compaq Expanded Memory Manager,'' a memory manager which is incompatible with Windows 3.x. * ''CHARSET.COM'' installs an alternative character set and font (called THINUS) to improve the text display on the internal gas plasma display * ''CLOCK.SYS'' a driver for the real time clock of the Portable 386 * ''MODE.COM'' replaced the default MODE.COM application of MS-DOS and allows additional commands like "MODE SEL MDA", "MODE SEL CGA", "MODE SPEED HIGH", "MODE SPEED LOW" to switch on the fly between the Portable's graphics and CPU frequency modes. * ''VDISK.SYS'' is a

virtual disk Virtual disk and virtual drive are software components that emulate an actual disk storage device. Virtual disks and virtual drives are common components of virtual machines in hardware virtualization, but they are also widely used for various p ...

driver which makes use of the RAM.

References

386 {{microcompu-stub