IBM 5100

The IBM 5100 laptop is a laptop (one of the first) introduced in September 1975, six years before the IBM personal computer. This is the evolution of a prototype called SCAMP (Special APL Machine Portable) that was developed at the IBM Scientific Center in Palo Alto in 1973. In January 1978, IBM announced IBM 5110, its most important cousin, and in February 1980 IBM announced The 5100 was removed in March 1982. When the IBM PC was introduced in 1981, it was originally designated as IBM 5150, putting it in the “5100” series, although its architecture was not not directly from the IBM 5100.

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 refers to the PALM module as a controller. The PALM could directly address 64 KiB of memory. Some configurations of the IBM 5100 had an executable ROS (ROM) memory and RAM memory totaling more than 64 KiB, so a simple bank switch scheme was used. The actual APL and BASIC interpreters have been stored in a separate Language ROS address space that PALM considers to be a device. Prices ranged from $ 11,000 ($ 16,000 model) to $ 20,000 ($ 64,000).

BYTE in December 1975 said “Welcome, IBM, to personal computing”. Describing the 5100 as “a pack of 50 books of interactive personal computers”, the magazine said that with the company’s announcement “personal computing is gaining an entrance from the giant of production and service”, but ” at a high price “. A single integrated unit provided the keyboard, the five-inch CRT display, the tape drive, the processor, several hundred KiB of system memory containing system software, and up to 64 KiB of RAM. It was about the size of a small suitcase, weighed about 55 lbs (25 kg) and could be carried in an optional carrying case, hence the “portable” designation. In 1975, it was an incredible technical achievement to pack a complete computer with a large amount of ROM and RAM, a CRT display, and a tape drive into such a small machine; Two years have elapsed before the release of the Commodore PET, similar but much cheaper. Older desktops of about the same size, such as the HP 9830, did not include a CRT or nearly as much memory. An IBM computer equivalent to the late 1960s would have been almost as large as two offices and would have weighed about half a ton.

The 5100 has an internal CRT (5 “diagonal) and displays 16 lines of 64 characters. IBM provides an option switch to allow the user to display all 64 characters of each line, or only the 32 characters left or right (interspersed with spaces) There was also a switch to display the first 512 bytes of the main memory in hexadecimal for diagnostic purposes.

The IBM solution has been provided by quarter-inch magnetic tape (QIC) tape drives that use standard DC300 cartridges to store 204 kilobytes. A reader was installed in the machine and a second one (model 5106) could be added in an attached box. The data format included several types and was written in 512-byte records.

An external video monitor (or a modified television receiver) can be connected to the IBM 5100 via a BNC connector on the back panel. While the 5100 had a front-panel switch to choose between white on black or black-on-white for the internal display, this switch did not affect the external monitor, which only offered lit characters on a black background. The vertical scan rate was set at 60 Hz.

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