They used the more advanced version 2 of the Palm OS.
Palm OS, however, was written for a touch-sensitive 160- by 160-pixel screen.
The new system, Palm OS 5, offers better security, performance and support for wireless standards, the company said.
Palm OS and 16-bit Windows use a similar scheme for memory management.
Palm OS 1.0 is the original version present on the Pilot 1000 and 5000.
Palm OS 3.5 is the first version to include native 8-bit color support.
Palm OS has been involved in various lawsuits over the years.
Palm OS based devices and smartphones are also usable for reading books.
"Why is this system so slow compared with the Palm OS?"
It will also work with organizers running Palm OS 3.1 or later.