In May 1990, NEC marketed the 98NOTE SX as a high-end version of the 98NOTE notebook computer. The 98NOTE SX came in two models: the PC-9801NS (a floppy disk model) and the PC-9801NS-20 (a hard disk model). Its main feature was that it was the first notebook computer in Japan equipped with a 32-bit microprocessor.
- Since these machines used the 386SX (with a clock frequency of 12megahertz) for their CPU, processing speed was improved to about double that of the 98NOTE. It was also possible to run 32-bit compatible software such as Japanese-language version MS-WINDOWS/386.
- The hard disk model was equipped with a 2.5-inch hard disk drive with a capacity of 20 megabytes, so it was possible to process large volumes of data at high speed, and multiple software applications could be efficiently managed.
- Both the floppy disk model and hard disk model had one built-in 1-megabyte 3.5-inch floppy disk drive and one 1.25-megabyte RAM drive with capacity corresponding to a single floppy disk drive, so they could both be used like a model equipped with two floppy disk drives. If the RAM drive was not used, the memory for the RAM drive could be used as 1 megabyte of user memory.
- Significant reductions in weight were achieved to bring the floppy disk model to 2.8kilograms, and the hard disk model to 2.95 kilograms. This was done by using 4-megabit DRAM, a slim type floppy disk drive, display and keyboard, and a compact 2.5-inch hard disk drive.