On April 3, 1986, IBM introduced the 5140 “Convertible.” It weighed 12 lbs., listed at $1,995, and had a grand total of 256K Random Access Memory, or “RAM.” It was considered a big improvement over its predecessor, the giant IBM Portable PC 5155, which was introduced in 1984. That model, which was much bulkier, had a handle on it, giving it “portability.”
The “Convertible” had a detachable miniature monitor, which theoretically allowed the user, with a monitor adapter, to hook up the unit to a larger, external monitor.
It was notable for its capacity to run on batteries, and from its being the first computer to utilize 3.5″ floppy disks.
One of several drawbacks was that with its smaller screen, typical letters were compressed to half their normal size (at this time, IBMs did not utilize a graphic interface).
In addition to the criticism of its screen and keyboard, there were a number of other problems which resulted in poor sales. The Convertible was heavier and no faster than its predecessor the 5155 (despite the innovations of a CMOS processor and static RAM), and didn’t include traditional PC expansion ports.
It also had to compete against faster portable computers based on the Intel 80286 processor made by Toshiba and Zenith – that were lighter and offered similar specifications, sometimes at half the price.