The IBM 5100 Portable Computer is one of the first portable computers, introduced in September 1975, six years before the IBM Personal Computer, and eight before the first successful IBM compatible portable computer, the Compaq Portable. It was the evolution of a prototype called the SCAMP (Special Computer APL Machine Portable) that was developed at the IBM Palo Alto Scientific Center in 1973. Whether considered evolutionary from SCAMP or revolutionary, it still needed to be plugged into an electric socket.
When the IBM PC was introduced in 1981, it was originally designated as the IBM 5150, putting it in the "5100" series, though its architecture was unrelated to the IBM 5100's. The 5100 was IBM's second transportable computer. Previously, a truck-based IBM 1401 configured in 1960 for military use was designated a portable computer, and nicknamed a DataMobile.
The IBM 5100 was withdrawn in March 1982, by which time IBM had announced its larger cousins, the IBM 5110 (January 1978) and the IBM 5120 (February 1980).
SCAMP, the prototype
In 1973, Bill Lowe was instrumental in fostering an engineering prototype called SCAMP (Special Computer APL Machine Portable) created by Dr. Paul Friedl and a team at the IBM Los Gatos Scientific Center. SCAMP has been dubbed in PC Magazine as "the world's first personal computer".
The IBM Los Gatos engineering prototype and a design model by IBM Industrial designer Tom Hardy, were utilized internally by Lowe in his early efforts to demonstrate the viability of creating a single-user computer.
SCAMP emulated an IBM 1130 minicomputer in order to run APL\1130. In 1973, APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP 9800 offered only BASIC.
Because SCAMP was the first to emulate APL\1130 performance on a portable, single user computer, PC Magazine in 1983 designated SCAMP a "revolutionary concept" and "the world's first personal computer".
Description
The IBM 5100 is based on a 16-bit processor module called PALM (Program All Logic in Microcode). The IBM 5100 Maintenance Information Manual also referred to the PALM module as the controller. The PALM could directly address of memory. Some configurations of the IBM 5100 had Executable ROS (ROM) and RAM memory totalling more than , so a simple bank switching scheme was used. The actual APL and BASIC interpreters were stored in a separate Language ROS address space which the PALM treats as a peripheral device. There were twelve models available: with BASIC, APL, or both. Memory could be , , or of main storage. The 5100 sold for between and (between $ and $ in today's dollars).
Often described as being "approximately fifty pounds", its weight was closer to 55 pounds (25 kg). In December 1975 BYTE stated "Welcome, IBM, to personal computing". Describing the 5100 as "a 50-lb package of interactive personal computing," the magazine said that with the company's announcement "personal computing gains an entry from the industry's production and service giant," albeit "at a premium price".
A single integrated unit provided the keyboard, five-inch CRT display, tape drive, processor, several hundred KB of read-only memory containing system software, and up to of RAM. It was the size of a small suitcase, weighed about (), and could be transported in an optional carrying case, hence the "portable" designation.
In 1975, it was an amazing technical accomplishment to package a complete computer with a large amount of ROM and RAM, CRT display, and a tape drive into a machine that small. Earlier desktop computers of approximately the same size, such as the HP 9830, did not include a CRT nor nearly as much memory. The 5100 has an internal CRT (five-inch diagonal) and displays 16 lines of 64 characters. IBM provided an option switch to allow the user to display all 64 characters of each line, or only the left or right 32 characters (interspersed with spaces). Also there was a switch to display the first 512 bytes of main memory in hexadecimal for diagnostic purposes.
Two solutions existed for obtaining hardcopy output: printers such as the IBM 5103, and attaching a typewriter via an interface. The TYCOM 5100 (from a company named Tycom Systems Corporation) enabled controlling an IBM Selectric typewriter, printing at 15.5 CPS.