IBM PC Convertible

The IBM PC Convertible is the first laptop published by IBM. Released on April 3, 1986, the convertible was also the first IBM computer to use the 3.5-inch floppy disk format that has become the industry standard. Like modern laptops, it included power management and the ability to run on batteries. It was the continuation of the IBM Portable and was the model number 5140. It was replaced in 1991 by the IBM PS / 2 L40 SX, and in Japan by IBM Personal System / 55note, which was the predecessor of the ThinkPad .

In 1983, IBM engineers reportedly developed a Tandy Model 100 laptop, dubbed “Sweetpea”, which Don Estridge rejected because it was not compatible with personal computers. In 1984, the largest LCD screen of another prototype (“P-14”) would have failed the “Chiclet Rule”, especially after the poor receipt of the Data General-One display.

The Convertible PC used the CMOS version of the Intel processor running at 4.77 MHz, 256 KB RAM (expandable to 640 KB), two 720 KB floppy drives, and a CGA-compatible monochrome LCD at a cost of $ 2,000. It weighed 5.8 kg (13 lb) and was equipped with a built-in carrying handle. The Convertible PC had expandability capabilities through a proprietary ISA-based port on the back of the machine. extension, including a small printer and a video output module The machine could also take an internal modem, but there was no room for an internal hard drive.The concept and design of the body was made by the designer industrial German Richard Sapper.Pressing the power button on the computer does not turn it off, but puts the machine in “suspended” mode, which remains in place as long as there is battery, which avoids the long start-up process. its state indefinitely by stopping the clock of the oscillator system. It can resume processing when the clock signal is restarted, as long as it is kept powered on. The CMOS 80C88 processor uses very little power when the clock signal is stopped. The system’s RAM in the cabriolet is SRAM rather than DRAM, both for low power consumption and fewer circuitry to fit into the cramped laptop case. The convertible had 256k of RAM included, with 128k (and possibly also 256k) memory cards available. There was space for 4 memory cards in the system, so at least one of these must be a 256k card in order to upgrade the system to a 640k base memory. The screen only measured half the size of the lid, so text characters and graphics were compressed vertically, half their normal height. The display was capable of 80×25 texts and graphic modes of 640×200 and 320×200 pixels. By pressing a lever between the two floppy drives just below the screen, the entire screen has been detached from the device. This feature allowed for the convenient use of a large-format desktop monitor on his desktop, a precursor to the docking concept, as well as Apple’s PowerBook Duo.

The machine sold very poorly for a number of reasons. The cabriolet was heavy, not much faster than the laptop it replaced (despite the new CMOS processor and the use of static RAM), did not come with traditional PC expansion ports (such as serial ports and a parallel port) without an add-on, and had a weird LCD screen hard to read (the first screens lacked backlight). It also competed with the faster Intel 80286-based laptops that offered optional hard drives, companies like Compaq, and laptops from companies like Toshiba and Zenith that were lighter and offered similar specifications, sometimes half price. The keyboard has also been widely criticized.

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