IBM 5100
| Company type | Product |
|---|---|
| Industry | Computer hardware |
| Predecessor | IBM 1401 (truck-mounted) |
| Founded | September 1975 |
| Successor | IBM 5110, IBM 5120 |
| Products | Portable computer |
IBM 5100 Portable Computer
Launched in September 1975, the IBM 5100 Portable Computer ranks among the pioneering portable computing devices, arriving six years prior to the IBM Personal Computer and eight years before the popular IBM-compatible Compaq Portable. Its design originated from the SCAMP (Special Computer APL Machine Portable) prototype created at IBM’s Los Gatos Laboratory and Palo Alto Scientific Center in 1973. Although promoted as portable, the device still needed to be plugged into an electrical outlet.
While categorized within the "5100" lineup, the IBM PC released in 1981 as the IBM 5150 featured a distinct architecture. The 5100 represented IBM's second transportable computer, succeeding the truck-mounted IBM 1401 configured for military applications in 1960.
Production of the IBM 5100 ceased in March 1982 following the introduction of its larger successors: the IBM 5110 in January 1978 and the IBM 5120 in February 1980.
SCAMP, the prototype
In 1973, Bill Lowe advocated for an engineering prototype named SCAMP (Special Computer APL Machine Portable), developed under Dr. Paul Friedl and his team at IBM's Los Gatos Scientific Center. Subsequently, PC Magazine referred to SCAMP as "the world's first personal computer".
The SCAMP prototype from IBM Los Gatos, along with a design model by IBM Industrial designer Tom Hardy, underpinned Lowe’s early initiative to demonstrate the feasibility of a computer intended for individual users.
SCAMP simulated an IBM 1130 minicomputer to execute APL\1130. At that time, APL was predominantly available only on mainframes, whereas most microcomputers such as the Wang 2200 or HP 9800 supported only BASIC. Because it could replicate APL\1130 functionality on a compact single-user device, PC Magazine in 1983 hailed SCAMP as a "revolutionary concept" and recognized it as "the world's first personal computer".
Description
At its core, the IBM 5100 utilizes a 16-bit PALM (Program All Logic in Microcode) processor module. The PALM directly accessed up to of memory; certain configurations extended this capacity through straightforward bank switching. The interpreters for APL and BASIC were housed within a distinct Language ROS address space treated as a peripheral device. Customers could choose from twelve models featuring BASIC, APL, or both languages, with memory options ranging from to .
Retailing between and , which equates to approximately $ to $ today, the IBM 5100 was positioned as a high-end product.
Weighing roughly 55 pounds (25 kg), it integrated a keyboard, five-inch CRT display, tape drive, processor, system software stored in ROM, and up to RAM within a suitcase-sized portable chassis. This level of integration was considered a major technological accomplishment in 1975 compared to contemporaries like the HP 9830, which lacked built-in displays or similar memory capacities.
The built-in CRT showed 16 lines of 64 characters with selectable display modes for users. Diagnostic capabilities included viewing memory contents in hexadecimal format.
For printed output, IBM provided options such as the IBM 5103 printer or interfaces compatible with typewriters like the TYCOM 5100, which operated an IBM Selectric typewriter at speeds of 15.5 characters per second.
Mass storage relied on removable quarter-inch cartridge (QIC) magnetic tapes holding per cartridge. One tape drive was integrated; an additional external drive could be connected (Model 5106). Floppy disk drives became available later with the introduction of the IBM 5110.
The IBM 5100 Communications Adapter allowed data exchange compatible with IBM 2741 terminals using EBCD notation, enabling seamless integration with existing systems. An optional Serial I/O Adapter facilitated connection and programming of any standard serial device outside IBM’s proprietary environment, enhancing adaptability.
An external video monitor could be attached via a BNC connector; however, only white-on-black display output was supported externally despite internal display color options. The vertical scan rate remained fixed at .
Research Device Coupler
An article titled "The IBM 5100 and the Research Device Coupler — A personal laboratory automation system," published in the IBM Systems Journal, Volume 16, Number 1, Page 41 (1977), outlined a compact configuration integrating the IBM 5100 Portable Computer with the Research Device Coupler. This arrangement provided a dedicated computer supporting high-level programming languages alongside a flexible interface for data acquisition and control, capable of handling experimental data rates up to 9600 baud. The Research Device Coupler served as an early prototype for what would become the IBM 7406 Device Coupler.
Programming languages
The IBM 5100 was available with either APL, BASIC, or both programming languages. At the time of its release, APL was predominantly found on mainframe systems, whereas most desktop machines such as the Wang 2200 or HP 9830 were limited to BASIC. By offering APL on a desktop platform, the 5100 positioned itself competitively against earlier models like the MCM/70.
Models equipped to handle both languages incorporated a front-panel toggle switch allowing users to choose between APL (switch up) and BASIC (switch down).
Beta tester Donald Polonis observed that the necessity for users to learn APL could restrict widespread acceptance, highlighting that user-friendliness was essential for personal computing devices. Despite APL’s sophisticated capabilities in vector and matrix operations, its distinctive character set and keyboard layout presented significant learning hurdles—a challenge that competitors such as the HP 9830 addressed by providing supplementary ROM extensions.
Although not designed for general consumers, the maintenance manual disclosed a specific keyboard sequence that activated a maintenance mode. This mode granted direct access to RAM, video memory, CPU registers, interrupt controls, and additional system components through hexadecimal commands resembling assembly language instructions. Such access enabled advanced programming techniques and ensured stable multitasking without relying on an operating system.
Emulator in microcode
The IBM 5100 utilized an innovative strategy by implementing an emulator constructed in microcode, allowing a compact and cost-efficient machine to execute software originally developed for larger, more costly computers—thus circumventing the expense and delay associated with rewriting applications.
This system incorporated two principal interpreters: a tailored version of APLSV, IBM’s APL interpreter designed for System/370 mainframes, along with the BASIC interpreter derived from IBM’s System/3 minicomputer. Consequently, its microcode emulated substantial aspects of both System/370 and System/3 operating environments.
IBM revisited this method in 1983 with the introduction of the XT/370, an IBM PC XT model equipped with a System/370 emulator expansion card.
Further reading
External links
- IBM 5100 Portable Computer
- IBM 5100 | oldcomputers.net
- IBM 5100 | oldcomputermuseum.com