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In 1981 IBM decided to move beyond the mainframes it had been building for decades and launch its first mass market personal computer, the IBM 5150.
The PC was a success for IBM — particularly in the office market — shipping more than 800,000 units in the two years after it went on sale. What helped drive the machine’s popularity was both the familiarity of the IBM name and the broad range of peripherals and software available for the computer.
The machine spawned a market in IBM-PC clones, known as IBM PC compatibles, made possible by the fact that the machines were built using off the shelf non-IBM hardware and that Microsoft was free to licence DOS for use on third-party machines. The spread of IBM PC compatible machines created a common standard for PCs, simplifying the process of buying a PC by ensuring that any IBM compatible PC would run the same software, no matter which company made it.
The machine's starting price was $1,565, it ran on a 4.77Mhz Intel 8088 microprocessor, came with a keyboard, ran Microsoft DOS, supported up to 256KB of RAM and a colour display, came with an optional 160K floppy disc drive and an optional colour monitor.
This machine is attached to an IBM PC monochrome display and an IBM dot-matrix printer.
The IBM PC monitor, announced in 1981, could output both text and graphics.
It could manage two graphics modes, a resolution of 320 x 200 pixels with up to four colours or 640 x 200 pixels with a monochrome display.
The monitor had four text modes, based on either 40 columns by 25 lines or 80 columns by 25 lines, with up to 16 colours.
It was usually driven by an IBM PC Color/Graphics Adapter (CGA), which included a Motorola MC6845 display controller and 16KB of video memory. It had a 4-bit RGB1 interface.
The IBM 5155 Portable PC might weigh as much as a small suitcase but it was portable, something that couldn't be said of most computers when it was released in 1984.
The machine was deemed "luggable", a reference to its heft and the fact it weighed a not inconsiderable 30 pounds — roughly 30 times more than an iPad Air.
Inside the computer was an IBM PC XT motherboard with an Intel 8088 processor running at 4.77MHz (the same as the original IBM PC).
It came with 256KB of RAM, expandable to 640KB. It had one or two 360KB half-height 5.25-inch diskette (floppy disk) drives and an IBM PC colour graphics adapter driving a built-in nine-inch orange monochrome CRT display.
The Portable PC's operating system was IBM PC Dos 2.1 or later.