IBM 5100

The IBM 5100 Portable Computer was a desktop computer introduced in September 1975, six years before the IBM PC. A single integrated unit provided the keyboard, five-inch CRT display, tape drive, processor, several hundred Kbytes of read only memory containing system software, and up to 64 K of random access memory. It was the size of a small suitcase, weighed about 55 lb (25 kg), and could be transported in an optional carrying case, hence the "portable" moniker.

While the IBM 5100 seems large today, 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. An equivalent late-1960's IBM computer would have been nearly as large as two desks and would have weighed about half a ton.

Available in 12 models providing 16 K, 32 K, 48 K or 64 K bytes of main storage, the 5100 sold for between $8,975 and $19,975. The 5100 was available with either APL or BASIC — or both — programming languages.

Machines that supported both languages provided a toggle switch on the front panel to select the language. When the engineers at IBM asked one beta tester, Donald Polonis, for his analysis, he commented that if folks had to learn APL to use it, the IBM 5100 would not make it as a personal computer. He tried to impress the fact that a personal computer had to be easy to use to be accepted.

IBM offered three Problem-Solver Libraries, contained in magnetic tape cartridges, with the IBM 5100 to provide more than 1000 interactive routines applicable to mathematical problems, statistical techniques and financial analyses.

The IBM 5100 is based on a 16-bit processor module called PALM (Put All Logic in Microcode). The IBM 5100 Maintenance Information Manual also referred to the PALM module as the controller. PALM can directly address 64 Kbytes of memory. Some configurations of the IBM 5100 had Executable ROS (ROM) and RAM memory totalling more than 64 Kbytes, so a simple bank switching scheme was used. The actual APL and/or BASIC interpeters were stored in a separate Language ROS address space which the PALM treats as a peripheral device.

An external video monitor (or modified television receiver) could be connected to the IBM 5100 via a BNC connector on the back panel. While the 5100 had a front panel switch to select between white on black or black on white for the internal display, this switch did not affect the external monitor, which only offered bright characters on a black blackground. The vertical scan rate was fixed at 60 Hz, which may have been inconvenient for users in countries using 50 Hz broadcast television systems (e.g., many European and South American countries).

Also in September 1975 IBM announced the IBM 5100 Communications Adapter. That allowed the 5100 to transmit data to and receive data from a remote system. It made the 5100 appear the same as an IBM 2741 Communications Terminal and in theory was able to communicate with IBM 2741 compatible machines in start-stop mode using the EBCD (Extended Binary Coded Decimal) notation. EBCD was similar to the more common IBM EBCDIC code, but not identical.

In Volume 16, Number 1, Page 41 (1977) of the IBM Systems Journal the article "The IBM 5100 and the Research Device Coupler — A personal laboratory automation system" read: "A small laboratory automation system has been developed by using the IBM 5100 Portable Computer in conjunction with the Research Device Coupler. This compact system provides a dedicated, high-level-language computer and a versatile data acquisition and control interface for experiments in which data rates do not exceed 9600 Baud. Two experiments exemplify the use of the system. The Research Device Coupler described in this paper is a prototype of the IBM 7406 Device Coupler."

The 5100 was withdrawn from marketing in March 1982. In January 1978 IBM announced its successor: The IBM 5110.

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 wasn't directly descended from the IBM 5100.

See also

• IBM
• IBM 5110 Portable Computer
• IBM 5120 Computing System
• IBM PALM processor
• Personal computer
• John Titor

External link

• IBM 5100 Portable Computer (http://www.brouhaha.com/~eric/retrocomputing/ibm/5100/)
• John Titor's IBM 5100/5110 (http://timetravelportal.com/viewtopic.php?t=41) - including specs, manuals and picturesfr:IBM 5100 et 5110