IBM PC Convertible
| Company type | Product model |
|---|---|
| Industry | Computer hardware |
| Predecessor | IBM Portable |
| Founded | April 1986 |
| Defunct | 1989 |
| Successor | IBM PS/2 Model L40 SX, IBM Personal System/55note |
Key people | Richard Sapper (industrial designer) |
| Products | Laptop computer |
The IBM PC Convertible (model 5140), launched in April 1986, represented IBM’s inaugural entry into the laptop category, following the earlier luggable IBM Portable. This model introduced IBM’s first use of the then-new 3½-inch floppy disk format, which improved both portability and data storage convenience. It incorporated early innovations in power management and featured battery operation, catering to the growing demand for mobile computing solutions.
Production of this model ended in 1989, with the IBM PS/2 Model L40 SX taking its place. In the Japanese market, it was succeeded by the IBM Personal System/55note, a forerunner to the notable ThinkPad line.
Predecessors
Prior to developing the Convertible, IBM explored laptop concepts. In 1983, a project known as "Sweetpea" sought to build a device similar to the Tandy Model 100 but was dismissed by Don Estridge due to its lack of PC compatible architecture. A subsequent prototype from 1984, called "P-14," did not pass IBM’s human factors evaluations, particularly after unfavorable comparisons with the display quality of the rival Data General-One.
Description
The PC Convertible was offered in three variants: the initial PC Convertible, followed by Model 2 and Model 3 versions introduced in October 1987. The primary distinction among these later models lay in their LCD screens. The original featured a non-backlit display that was often criticized for poor readability; Model 2 upgraded to a supertwist LCD without backlighting, while Model 3 added a backlight feature. Aside from these screen differences, hardware specifications remained largely unchanged across all versions.
Equipped with an Intel 80C88 processor—a CMOS variant of the Intel 8088—the base system included 256 KB of RAM expandable up to 640 KB, dual 720 KB 3.5-inch floppy disk drives, and a monochrome CGA-compatible LCD display. Weighing slightly over 12 pounds and featuring an integrated handle, it offered battery life up to ten hours for non-backlit models and around four hours for the backlit Model 3.
At launch, pricing started at $1,995 for the original model; Model 2 ranged between $1,395 (with 256K RAM) and $1,900 (with 640K RAM); Model 3 was available at $1,695 with 256K RAM.
The LCD supported an 80x25 character display with a wide aspect ratio that resulted in vertically compressed text and graphics. Supported graphics resolutions included 640x200 and 320x200 pixels.
Expansion options were provided through a proprietary ISA-based connector located on the rear of the unit, enabling attachment of snap-in accessories such as a compact printer or video output module. While an internal modem could be installed, there was no provision for an internal hard drive. The device’s design was overseen by German industrial designer Richard Sapper, who also developed black prototype versions.
The power switch placed the system into a "suspend" state rather than fully powering it down, maintaining system status while conserving battery life. The static-core CMOS processor halted its clock oscillator during suspend mode to preserve state indefinitely as long as power remained connected. To minimize energy consumption and save physical space, SRAM was utilized instead of DRAM.
A lever situated between the floppy drives allowed detachment of the screen from the main unit for use with an external desktop monitor—an early concept resembling today’s docking stations and comparable to Apple’s PowerBook Duo.
Reception
In 1989, InfoWorld described the PC Convertible as a "notable failure," primarily due to its steep cost and outdated technology. Commercially, the device underperformed, often regarded as lacking value when compared to rivals that provided more integrated features. Nonetheless, it gained some traction among corporate clients who appreciated its battery longevity and ease of transport.
The Model 3, released in October 1987, attempted to resolve certain shortcomings but still omitted built-in ports, necessitating the use of adapters for parallel, serial, and video interfaces—capabilities commonly included in competing products. Additionally, it was heavier and did not offer a significant speed improvement over the Portable model it succeeded. Its LCD display was criticized for limited clarity and an unusual form factor. Competitors such as Compaq, Toshiba, and Zenith delivered laptops that were lighter, faster, and often equipped with optional hard drives at more competitive prices. The keyboard was also noted for lacking several essential keys.
See also
External links
- IBM-5140 Convertible along with a collection of vintage digital and analog computers at oldcomputermuseum.com
- IBM PC Convertible brochure